summary refs log tree commit diff
path: root/doc/contributing.texi
blob: 40ae33ecacafd66c50b40297d59806089da5298f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
@node Contributing
@chapter Contributing

This project is a cooperative effort, and we need your help to make it
grow!  Please get in touch with us on @email{guix-devel@@gnu.org} and
@code{#guix} on the Libera Chat IRC network.  We welcome ideas, bug
reports, patches, and anything that may be helpful to the project.  We
particularly welcome help on packaging (@pxref{Packaging Guidelines}).

@cindex code of conduct, of contributors
@cindex contributor covenant
We want to provide a warm, friendly, and harassment-free environment, so
that anyone can contribute to the best of their abilities.  To this end
our project uses a ``Contributor Covenant'', which was adapted from
@url{https://contributor-covenant.org/}.  You can find a local version in
the @file{CODE-OF-CONDUCT} file in the source tree.

Contributors are not required to use their legal name in patches and
on-line communication; they can use any name or pseudonym of their
choice.

@menu
* Building from Git::           The latest and greatest.
* Running Guix Before It Is Installed::  Hacker tricks.
* The Perfect Setup::           The right tools.
* Packaging Guidelines::        Growing the distribution.
* Coding Style::                Hygiene of the contributor.
* Submitting Patches::          Share your work.
* Tracking Bugs and Patches::   Keeping it all organized.
* Commit Access::               Pushing to the official repository.
* Updating the Guix Package::   Updating the Guix package definition.
* Writing Documentation::       Improving documentation in GNU Guix.
* Translating Guix::            Make Guix speak your native language.
@end menu

@node Building from Git
@section Building from Git

If you want to hack Guix itself, it is recommended to use the latest
version from the Git repository:

@example
git clone https://git.savannah.gnu.org/git/guix.git
@end example

@cindex authentication, of a Guix checkout
How do you ensure that you obtained a genuine copy of the repository?
To do that, run @command{guix git authenticate}, passing it the commit
and OpenPGP fingerprint of the @dfn{channel introduction}
(@pxref{Invoking guix git authenticate}):

@c The commit and fingerprint below must match those of the channel
@c introduction in '%default-channels'.
@example
git fetch origin keyring:keyring
guix git authenticate 9edb3f66fd807b096b48283debdcddccfea34bad \
  "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA"
@end example

@noindent
This command completes with exit code zero on success; it prints an
error message and exits with a non-zero code otherwise.

As you can see, there is a chicken-and-egg problem: you first need to
have Guix installed.  Typically you would install Guix System
(@pxref{System Installation}) or Guix on top of another distro
(@pxref{Binary Installation}); in either case, you would verify the
OpenPGP signature on the installation medium.  This ``bootstraps'' the
trust chain.

The easiest way to set up a development environment for Guix is, of
course, by using Guix!  The following command starts a new shell where
all the dependencies and appropriate environment variables are set up to
hack on Guix:

@example
guix shell -D guix --pure
@end example

@xref{Invoking guix shell}, for more information on that command.

If you are unable to use Guix when building Guix from a checkout, the
following are the required packages in addition to those mentioned in the
installation instructions (@pxref{Requirements}).

@itemize
@item @url{https://gnu.org/software/autoconf/, GNU Autoconf};
@item @url{https://gnu.org/software/automake/, GNU Automake};
@item @url{https://gnu.org/software/gettext/, GNU Gettext};
@item @url{https://gnu.org/software/texinfo/, GNU Texinfo};
@item @url{https://www.graphviz.org/, Graphviz};
@item @url{https://www.gnu.org/software/help2man/, GNU Help2man (optional)}.
@end itemize

On Guix, extra dependencies can be added by instead running @command{guix
shell}:

@example
guix shell -D guix help2man git strace --pure
@end example

From there you can generate the build system infrastructure
using Autoconf and Automake:

@example
./bootstrap
@end example

If you get an error like this one:

@example
configure.ac:46: error: possibly undefined macro: PKG_CHECK_MODULES
@end example

@noindent
it probably means that Autoconf couldn’t find @file{pkg.m4}, which is
provided by pkg-config.  Make sure that @file{pkg.m4} is available.  The
same holds for the @file{guile.m4} set of macros provided by Guile.  For
instance, if you installed Automake in @file{/usr/local}, it wouldn’t
look for @file{.m4} files in @file{/usr/share}.  In that case, you have
to invoke the following command:

@example
export ACLOCAL_PATH=/usr/share/aclocal
@end example

@xref{Macro Search Path,,, automake, The GNU Automake Manual}, for
more information.

Then, run:

@example
./configure --localstatedir=/var
@end example

@noindent
... where @file{/var} is the normal @code{localstatedir} value
(@pxref{The Store}, for information about this).  Note that you will
probably not run @command{make install} at the end (you don't have to)
but it's still important to pass the right @code{localstatedir}.

Finally, you can build Guix and, if you feel so inclined, run the tests
(@pxref{Running the Test Suite}):

@example
make
make check
@end example

@noindent
If anything fails, take a look at installation instructions
(@pxref{Installation}) or send a message to the
@email{guix-devel@@gnu.org, mailing list}.

From there on, you can authenticate all the commits included in your
checkout by running:

@example
make authenticate
@end example

The first run takes a couple of minutes, but subsequent runs are faster.

Or, when your configuration for your local Git repository doesn't match
the default one, you can provide the reference for the @code{keyring}
branch through the variable @code{GUIX_GIT_KEYRING}.  The following
example assumes that you have a Git remote called @samp{myremote}
pointing to the official repository:

@example
make authenticate GUIX_GIT_KEYRING=myremote/keyring
@end example

@quotation Note
You are advised to run @command{make authenticate} after every
@command{git pull} invocation.  This ensures you keep receiving valid
changes to the repository.
@end quotation

After updating the repository, @command{make} might fail with an error
similar to the following example:

@example
error: failed to load 'gnu/packages/dunst.scm':
ice-9/eval.scm:293:34: In procedure abi-check: #<record-type <origin>>: record ABI mismatch; recompilation needed
@end example

This means that one of the record types that Guix defines (in this
example, the @code{origin} record) has changed, and all of guix needs
to be recompiled to take that change into account.  To do so, run
@command{make clean-go} followed by @command{make}.

@node Running Guix Before It Is Installed
@section Running Guix Before It Is Installed

In order to keep a sane working environment, you will find it useful to
test the changes made in your local source tree checkout without
actually installing them.  So that you can distinguish between your
``end-user'' hat and your ``motley'' costume.

To that end, all the command-line tools can be used even if you have not
run @code{make install}.  To do that, you first need to have an
environment with all the dependencies available (@pxref{Building from
Git}), and then simply prefix each command with @command{./pre-inst-env}
(the @file{pre-inst-env} script lives in the top build tree of Guix; it
is generated by running @command{./bootstrap} followed by
@command{./configure}).  As an example, here is how you would build the
@code{hello} package as defined in your working tree (this assumes
@command{guix-daemon} is already running on your system; it's OK if it's
a different version):

@example
$ ./pre-inst-env guix build hello
@end example

@noindent
Similarly, an example for a Guile session using the Guix modules:

@example
$ ./pre-inst-env guile -c '(use-modules (guix utils)) (pk (%current-system))'

;;; ("x86_64-linux")
@end example

@noindent
@cindex REPL
@cindex read-eval-print loop
@dots{} and for a REPL (@pxref{Using Guix Interactively}):

@example
$ ./pre-inst-env guile
scheme@@(guile-user)> ,use(guix)
scheme@@(guile-user)> ,use(gnu)
scheme@@(guile-user)> (define snakes
                       (fold-packages
                         (lambda (package lst)
                           (if (string-prefix? "python"
                                               (package-name package))
                               (cons package lst)
                               lst))
                         '()))
scheme@@(guile-user)> (length snakes)
$1 = 361
@end example

If you are hacking on the daemon and its supporting code or if
@command{guix-daemon} is not already running on your system, you can
launch it straight from the build tree@footnote{The @option{-E} flag to
@command{sudo} guarantees that @code{GUILE_LOAD_PATH} is correctly set
such that @command{guix-daemon} and the tools it uses can find the Guile
modules they need.}:

@example
$ sudo -E ./pre-inst-env guix-daemon --build-users-group=guixbuild
@end example

The @command{pre-inst-env} script sets up all the environment variables
necessary to support this, including @env{PATH} and @env{GUILE_LOAD_PATH}.

Note that @command{./pre-inst-env guix pull} does @emph{not} upgrade the
local source tree; it simply updates the @file{~/.config/guix/current}
symlink (@pxref{Invoking guix pull}).  Run @command{git pull} instead if
you want to upgrade your local source tree.

Sometimes, especially if you have recently updated your repository,
running @command{./pre-inst-env} will print a message similar to the
following example:

@example
;;; note: source file /home/user/projects/guix/guix/progress.scm
;;;       newer than compiled /home/user/projects/guix/guix/progress.go
@end example

This is only a note and you can safely ignore it.  You can get rid of
the message by running @command{make -j4}.  Until you do, Guile will run
slightly slower because it will interpret the code instead of using
prepared Guile object (@file{.go}) files.

You can run @command{make} automatically as you work using
@command{watchexec} from the @code{watchexec} package.  For example,
to build again each time you update a package file, run
@samp{watchexec -w gnu/packages -- make -j4}.

@node The Perfect Setup
@section The Perfect Setup

The Perfect Setup to hack on Guix is basically the perfect setup used
for Guile hacking (@pxref{Using Guile in Emacs,,, guile, Guile Reference
Manual}).  First, you need more than an editor, you need
@url{https://www.gnu.org/software/emacs, Emacs}, empowered by the
wonderful @url{https://nongnu.org/geiser/, Geiser}.  To set that up, run:

@example
guix install emacs guile emacs-geiser emacs-geiser-guile
@end example

Geiser allows for interactive and incremental development from within
Emacs: code compilation and evaluation from within buffers, access to
on-line documentation (docstrings), context-sensitive completion,
@kbd{M-.} to jump to an object definition, a REPL to try out your code,
and more (@pxref{Introduction,,, geiser, Geiser User Manual}).  For
convenient Guix development, make sure to augment Guile’s load path so
that it finds source files from your checkout:

@lisp
;; @r{Assuming the Guix checkout is in ~/src/guix.}
(with-eval-after-load 'geiser-guile
  (add-to-list 'geiser-guile-load-path "~/src/guix"))
@end lisp

To actually edit the code, Emacs already has a neat Scheme mode.  But in
addition to that, you must not miss
@url{https://www.emacswiki.org/emacs/ParEdit, Paredit}.  It provides
facilities to directly operate on the syntax tree, such as raising an
s-expression or wrapping it, swallowing or rejecting the following
s-expression, etc.

@cindex code snippets
@cindex templates
@cindex reducing boilerplate
We also provide templates for common git commit messages and package
definitions in the @file{etc/snippets} directory.  These templates can
be used to expand short trigger strings to interactive text snippets. If
you use @url{https://joaotavora.github.io/yasnippet/, YASnippet}, you
may want to add the @file{etc/snippets/yas} snippets directory to the
@var{yas-snippet-dirs} variable.  If you use
@url{https://github.com/minad/tempel/, Tempel}, you may want to add the
@file{etc/snippets/tempel/*} path to the @var{tempel-path} variable in
Emacs.

@lisp
;; @r{Assuming the Guix checkout is in ~/src/guix.}
;; @r{Yasnippet configuration}
(with-eval-after-load 'yasnippet
  (add-to-list 'yas-snippet-dirs "~/src/guix/etc/snippets/yas"))
;; @r{Tempel configuration}
(with-eval-after-load 'tempel
   ;; Ensure tempel-path is a list -- it may also be a string.
   (unless (listp 'tempel-path)
     (setq tempel-path (list tempel-path)))
   (add-to-list 'tempel-path "~/src/guix/etc/snippets/tempel/*"))
@end lisp

The commit message snippets depend on @url{https://magit.vc/, Magit} to
display staged files.  When editing a commit message type @code{add}
followed by @kbd{TAB} to insert a commit message template for adding a
package; type @code{update} followed by @kbd{TAB} to insert a template
for updating a package; type @code{https} followed by @kbd{TAB} to
insert a template for changing the home page URI of a package to HTTPS.

The main snippet for @code{scheme-mode} is triggered by typing
@code{package...} followed by @kbd{TAB}.  This snippet also inserts the
trigger string @code{origin...}, which can be expanded further.  The
@code{origin} snippet in turn may insert other trigger strings ending on
@code{...}, which also can be expanded further.

@cindex insert or update copyright
@cindex @code{M-x guix-copyright}
@cindex @code{M-x copyright-update}
We additionally provide insertion and automatic update of a copyright in
@file{etc/copyright.el}.  You may want to set your full name, mail, and
load a file.

@lisp
(setq user-full-name "Alice Doe")
(setq user-mail-address "alice@@mail.org")
;; @r{Assuming the Guix checkout is in ~/src/guix.}
(load-file "~/src/guix/etc/copyright.el")
@end lisp

To insert a copyright at the current line invoke @code{M-x guix-copyright}.

To update a copyright you need to specify a @code{copyright-names-regexp}.

@lisp
(setq copyright-names-regexp
      (format "%s <%s>" user-full-name user-mail-address))
@end lisp

You can check if your copyright is up to date by evaluating @code{M-x
copyright-update}.  If you want to do it automatically after each buffer
save then add @code{(add-hook 'after-save-hook 'copyright-update)} in
Emacs.

@node Packaging Guidelines
@section Packaging Guidelines

@cindex packages, creating
The GNU distribution is nascent and may well lack some of your favorite
packages.  This section describes how you can help make the distribution
grow.

Free software packages are usually distributed in the form of
@dfn{source code tarballs}---typically @file{tar.gz} files that contain
all the source files.  Adding a package to the distribution means
essentially two things: adding a @dfn{recipe} that describes how to
build the package, including a list of other packages required to build
it, and adding @dfn{package metadata} along with that recipe, such as a
description and licensing information.

In Guix all this information is embodied in @dfn{package definitions}.
Package definitions provide a high-level view of the package.  They are
written using the syntax of the Scheme programming language; in fact,
for each package we define a variable bound to the package definition,
and export that variable from a module (@pxref{Package Modules}).
However, in-depth Scheme knowledge is @emph{not} a prerequisite for
creating packages.  For more information on package definitions,
@pxref{Defining Packages}.

Once a package definition is in place, stored in a file in the Guix
source tree, it can be tested using the @command{guix build} command
(@pxref{Invoking guix build}).  For example, assuming the new package is
called @code{gnew}, you may run this command from the Guix build tree
(@pxref{Running Guix Before It Is Installed}):

@example
./pre-inst-env guix build gnew --keep-failed
@end example

Using @code{--keep-failed} makes it easier to debug build failures since
it provides access to the failed build tree.  Another useful
command-line option when debugging is @code{--log-file}, to access the
build log.

If the package is unknown to the @command{guix} command, it may be that
the source file contains a syntax error, or lacks a @code{define-public}
clause to export the package variable.  To figure it out, you may load
the module from Guile to get more information about the actual error:

@example
./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
@end example

Once your package builds correctly, please send us a patch
(@pxref{Submitting Patches}).  Well, if you need help, we will be happy to
help you too.  Once the patch is committed in the Guix repository, the
new package automatically gets built on the supported platforms by
@url{https://@value{SUBSTITUTE-SERVER-1}, our continuous integration system}.

@cindex substituter
Users can obtain the new package definition simply by running
@command{guix pull} (@pxref{Invoking guix pull}).  When
@code{@value{SUBSTITUTE-SERVER-1}} is done building the package, installing the
package automatically downloads binaries from there
(@pxref{Substitutes}).  The only place where human intervention is
needed is to review and apply the patch.


@menu
* Software Freedom::            What may go into the distribution.
* Package Naming::              What's in a name?
* Version Numbers::             When the name is not enough.
* Synopses and Descriptions::   Helping users find the right package.
* Snippets versus Phases::      Whether to use a snippet, or a build phase.
* Emacs Packages::              Your Elisp fix.
* Python Modules::              A touch of British comedy.
* Perl Modules::                Little pearls.
* Java Packages::               Coffee break.
* Rust Crates::                 Beware of oxidation.
* Elm Packages::                Trees of browser code
* Fonts::                       Fond of fonts.
@end menu

@node Software Freedom
@subsection Software Freedom

@c Adapted from http://www.gnu.org/philosophy/philosophy.html.
@cindex free software
The GNU operating system has been developed so that users can have
freedom in their computing.  GNU is @dfn{free software}, meaning that
users have the @url{https://www.gnu.org/philosophy/free-sw.html,four
essential freedoms}: to run the program, to study and change the program
in source code form, to redistribute exact copies, and to distribute
modified versions.  Packages found in the GNU distribution provide only
software that conveys these four freedoms.

In addition, the GNU distribution follow the
@url{https://www.gnu.org/distros/free-system-distribution-guidelines.html,free
software distribution guidelines}.  Among other things, these guidelines
reject non-free firmware, recommendations of non-free software, and
discuss ways to deal with trademarks and patents.

Some otherwise free upstream package sources contain a small and optional
subset that violates the above guidelines, for instance because this subset
is itself non-free code.  When that happens, the offending items are removed
with appropriate patches or code snippets in the @code{origin} form of the
package (@pxref{Defining Packages}).  This way, @code{guix
build --source} returns the ``freed'' source rather than the unmodified
upstream source.


@node Package Naming
@subsection Package Naming

@cindex package name
A package actually has two names associated with it.
First, there is the name of the @emph{Scheme variable}, the one following
@code{define-public}.  By this name, the package can be made known in the
Scheme code, for instance as input to another package.  Second, there is
the string in the @code{name} field of a package definition.  This name
is used by package management commands such as
@command{guix package} and @command{guix build}.

Both are usually the same and correspond to the lowercase conversion of
the project name chosen upstream, with underscores replaced with
hyphens.  For instance, GNUnet is available as @code{gnunet}, and
SDL_net as @code{sdl-net}.

A noteworthy exception to this rule is when the project name is only a
single character, or if an older maintained project with the same name
already exists---regardless of whether it has already been packaged for
Guix.  Use common sense to make such names unambiguous and meaningful.
For example, Guix's package for the shell called ``s'' upstream is
@code{s-shell} and @emph{not} @code{s}.  Feel free to ask your fellow
hackers for inspiration.

We do not add @code{lib} prefixes for library packages, unless these are
already part of the official project name.  But @pxref{Python
Modules} and @ref{Perl Modules} for special rules concerning modules for
the Python and Perl languages.

Font package names are handled differently, @pxref{Fonts}.


@node Version Numbers
@subsection Version Numbers

@cindex package version
We usually package only the latest version of a given free software
project.  But sometimes, for instance for incompatible library versions,
two (or more) versions of the same package are needed.  These require
different Scheme variable names.  We use the name as defined
in @ref{Package Naming}
for the most recent version; previous versions use the same name, suffixed
by @code{-} and the smallest prefix of the version number that may
distinguish the two versions.

The name inside the package definition is the same for all versions of a
package and does not contain any version number.

For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:

@lisp
(define-public gtk+
  (package
    (name "gtk+")
    (version "3.9.12")
    ...))
(define-public gtk+-2
  (package
    (name "gtk+")
    (version "2.24.20")
    ...))
@end lisp
If we also wanted GTK+ 3.8.2, this would be packaged as
@lisp
(define-public gtk+-3.8
  (package
    (name "gtk+")
    (version "3.8.2")
    ...))
@end lisp

@c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
@c for a discussion of what follows.
@cindex version number, for VCS snapshots
Occasionally, we package snapshots of upstream's version control system
(VCS) instead of formal releases.  This should remain exceptional,
because it is up to upstream developers to clarify what the stable
release is.  Yet, it is sometimes necessary.  So, what should we put in
the @code{version} field?

Clearly, we need to make the commit identifier of the VCS snapshot
visible in the version string, but we also need to make sure that the
version string is monotonically increasing so that @command{guix package
--upgrade} can determine which version is newer.  Since commit
identifiers, notably with Git, are not monotonically increasing, we add
a revision number that we increase each time we upgrade to a newer
snapshot.  The resulting version string looks like this:

@example
2.0.11-3.cabba9e
  ^    ^    ^
  |    |    `-- upstream commit ID
  |    |
  |    `--- Guix package revision
  |
latest upstream version
@end example

It is a good idea to strip commit identifiers in the @code{version}
field to, say, 7 digits.  It avoids an aesthetic annoyance (assuming
aesthetics have a role to play here) as well as problems related to OS
limits such as the maximum shebang length (127 bytes for the Linux
kernel).  There are helper functions for doing this for packages using
@code{git-fetch} or @code{hg-fetch} (see below).  It is best to use the
full commit identifiers in @code{origin}s, though, to avoid ambiguities.
A typical package definition may look like this:


@lisp
(define my-package
  (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
        (revision "1"))          ;Guix package revision
    (package
      (version (git-version "0.9" revision commit))
      (source (origin
                (method git-fetch)
                (uri (git-reference
                      (url "git://example.org/my-package.git")
                      (commit commit)))
                (sha256 (base32 "1mbikn@dots{}"))
                (file-name (git-file-name name version))))
      ;; @dots{}
      )))
@end lisp

@deffn {Scheme Procedure} git-version @var{VERSION} @var{REVISION} @var{COMMIT}
Return the version string for packages using @code{git-fetch}.

@lisp
(git-version "0.2.3" "0" "93818c936ee7e2f1ba1b315578bde363a7d43d05")
@result{} "0.2.3-0.93818c9"
@end lisp
@end deffn

@deffn {Scheme Procedure} hg-version @var{VERSION} @var{REVISION} @var{CHANGESET}
Return the version string for packages using @code{hg-fetch}.  It works
in the same way as @code{git-version}.
@end deffn

@node Synopses and Descriptions
@subsection Synopses and Descriptions

@cindex package description
@cindex package synopsis
As we have seen before, each package in GNU@tie{}Guix includes a
synopsis and a description (@pxref{Defining Packages}).  Synopses and
descriptions are important: They are what @command{guix package
--search} searches, and a crucial piece of information to help users
determine whether a given package suits their needs.  Consequently,
packagers should pay attention to what goes into them.

Synopses must start with a capital letter and must not end with a
period.  They must not start with ``a'' or ``the'', which usually does
not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
tool that frobs files''.  The synopsis should say what the package
is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
matching a pattern''.

Keep in mind that the synopsis must be meaningful for a very wide
audience.  For example, ``Manipulate alignments in the SAM format''
might make sense for a seasoned bioinformatics researcher, but might be
fairly unhelpful or even misleading to a non-specialized audience.  It
is a good idea to come up with a synopsis that gives an idea of the
application domain of the package.  In this example, this might give
something like ``Manipulate nucleotide sequence alignments'', which
hopefully gives the user a better idea of whether this is what they are
looking for.

Descriptions should take between five and ten lines.  Use full
sentences, and avoid using acronyms without first introducing them.
Please avoid marketing phrases such as ``world-leading'',
``industrial-strength'', and ``next-generation'', and avoid superlatives
like ``the most advanced''---they are not helpful to users looking for a
package and may even sound suspicious.  Instead, try to be factual,
mentioning use cases and features.

@cindex Texinfo markup, in package descriptions
Descriptions can include Texinfo markup, which is useful to introduce
ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}).  However you
should be careful when using some characters for example @samp{@@} and
curly braces which are the basic special characters in Texinfo
(@pxref{Special Characters,,, texinfo, GNU Texinfo}).  User interfaces
such as @command{guix show} take care of rendering it
appropriately.

Synopses and descriptions are translated by volunteers
@uref{https://translate.fedoraproject.org/projects/guix/packages, at
Weblate} so that as many users as possible can read them in
their native language.  User interfaces search them and display them in
the language specified by the current locale.

To allow @command{xgettext} to extract them as translatable strings,
synopses and descriptions @emph{must be literal strings}.  This means
that you cannot use @code{string-append} or @code{format} to construct
these strings:

@lisp
(package
  ;; @dots{}
  (synopsis "This is translatable")
  (description (string-append "This is " "*not*" " translatable.")))
@end lisp

Translation is a lot of work so, as a packager, please pay even more
attention to your synopses and descriptions as every change may entail
additional work for translators.  In order to help them, it is possible
to make recommendations or instructions visible to them by inserting
special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
Gettext}):

@lisp
;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
(description "ARandR is designed to provide a simple visual front end
for the X11 resize-and-rotate (RandR) extension. @dots{}")
@end lisp

@node Snippets versus Phases
@subsection Snippets versus Phases

@cindex snippets, when to use
The boundary between using an origin snippet versus a build phase to
modify the sources of a package can be elusive.  Origin snippets are
typically used to remove unwanted files such as bundled libraries,
nonfree sources, or to apply simple substitutions.  The source derived
from an origin should produce a source that can be used to build the
package on any system that the upstream package supports (i.e., act as
the corresponding source).  In particular, origin snippets must not
embed store items in the sources; such patching should rather be done
using build phases.  Refer to the @code{origin} record documentation for
more information (@pxref{origin Reference}).

@node Emacs Packages
@subsection Emacs Packages

@cindex emacs, packaging
@cindex elisp, packaging
Emacs packages should preferably use the Emacs build system
(@pxref{emacs-build-system}), for uniformity and the benefits provided
by its build phases, such as the auto-generation of the autoloads file
and the byte compilation of the sources.  Because there is no
standardized way to run a test suite for Emacs packages, tests are
disabled by default.  When a test suite is available, it should be
enabled by setting the @code{#:tests?} argument to @code{#true}.  By
default, the command to run the test is @command{make check}, but any
command can be specified via the @code{#:test-command} argument.  The
@code{#:test-command} argument expects a list containing a command and
its arguments, to be invoked during the @code{check} phase.

The Elisp dependencies of Emacs packages are typically provided as
@code{propagated-inputs} when required at run time.  As for other
packages, build or test dependencies should be specified as
@code{native-inputs}.

Emacs packages sometimes depend on resources directories that should be
installed along the Elisp files.  The @code{#:include} argument can be
used for that purpose, by specifying a list of regexps to match.  The
best practice when using the @code{#:include} argument is to extend
rather than override its default value (accessible via the
@code{%default-include} variable).  As an example, a yasnippet extension
package typically include a @file{snippets} directory, which could be
copied to the installation directory using:

@lisp
#:include (cons "^snippets/" %default-include)
@end lisp

When encountering problems, it is wise to check for the presence of the
@code{Package-Requires} extension header in the package main source
file, and whether any dependencies and their versions listed therein are
satisfied.

@node Python Modules
@subsection Python Modules

@cindex python
We currently package Python 2 and Python 3, under the Scheme variable names
@code{python-2} and @code{python} as explained in @ref{Version Numbers}.
To avoid confusion and naming clashes with other programming languages, it
seems desirable that the name of a package for a Python module contains
the word @code{python}.

Some modules are compatible with only one version of Python, others with
both.  If the package Foo is compiled with Python 3, we name it
@code{python-foo}.  If it is compiled with Python 2, we name it
@code{python2-foo}.  Packages should be added when they are necessary;
we don't add Python 2 variants of the package unless we are going to use
them.

If a project already contains the word @code{python}, we drop this;
for instance, the module python-dateutil is packaged under the names
@code{python-dateutil} and @code{python2-dateutil}.  If the project name
starts with @code{py} (e.g.@: @code{pytz}), we keep it and prefix it as
described above.

@quotation Note
Currently there are two different build systems for Python packages in Guix:
@var{python-build-system} and @var{pyproject-build-system}.  For the
longest time, Python packages were built from an informally specified
@file{setup.py} file.  That worked amazingly well, considering Python's
success, but was difficult to build tooling around.  As a result, a host
of alternative build systems emerged and the community eventually settled on a
@url{https://peps.python.org/pep-0517/, formal standard} for specifying build
requirements.  @var{pyproject-build-system} is Guix's implementation of this
standard.  It is considered ``experimental'' in that it does not yet support
all the various PEP-517 @emph{build backends}, but you are encouraged to try
it for new Python packages and report any problems.  It will eventually be
deprecated and merged into @var{python-build-system}.
@end quotation

@subsubsection Specifying Dependencies
@cindex inputs, for Python packages

Dependency information for Python packages is usually available in the
package source tree, with varying degrees of accuracy: in the
@file{pyproject.toml} file, the @file{setup.py} file, in
@file{requirements.txt}, or in @file{tox.ini} (the latter mostly for
test dependencies).

Your mission, when writing a recipe for a Python package, is to map
these dependencies to the appropriate type of ``input'' (@pxref{package
Reference, inputs}).  Although the @code{pypi} importer normally does a
good job (@pxref{Invoking guix import}), you may want to check the
following check list to determine which dependency goes where.

@itemize

@item
We currently package Python with @code{setuptools} and @code{pip}
installed per default.  This is about to change, and users are encouraged
to use @code{python-toolchain} if they want a build environment for Python.

@command{guix lint} will warn if @code{setuptools} or @code{pip} are
added as native-inputs because they are generally not necessary.

@item
Python dependencies required at run time go into
@code{propagated-inputs}.  They are typically defined with the
@code{install_requires} keyword in @file{setup.py}, or in the
@file{requirements.txt} file.

@item
Python packages required only at build time---e.g., those listed under
@code{build-system.requires} in @file{pyproject.toml} or with the
@code{setup_requires} keyword in @file{setup.py}---or dependencies only
for testing---e.g., those in @code{tests_require} or @file{tox.ini}---go into
@code{native-inputs}.  The rationale is that (1) they do not need to be
propagated because they are not needed at run time, and (2) in a
cross-compilation context, it's the ``native'' input that we'd want.

Examples are the @code{pytest}, @code{mock}, and @code{nose} test
frameworks.  Of course if any of these packages is also required at
run-time, it needs to go to @code{propagated-inputs}.

@item
Anything that does not fall in the previous categories goes to
@code{inputs}, for example programs or C libraries required for building
Python packages containing C extensions.

@item
If a Python package has optional dependencies (@code{extras_require}),
it is up to you to decide whether to add them or not, based on their
usefulness/overhead ratio (@pxref{Submitting Patches, @command{guix
size}}).

@end itemize


@node Perl Modules
@subsection Perl Modules

@cindex perl
Perl programs standing for themselves are named as any other package,
using the lowercase upstream name.
For Perl packages containing a single class, we use the lowercase class name,
replace all occurrences of @code{::} by dashes and prepend the prefix
@code{perl-}.
So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
Modules containing several classes keep their lowercase upstream name and
are also prepended by @code{perl-}.  Such modules tend to have the word
@code{perl} somewhere in their name, which gets dropped in favor of the
prefix.  For instance, @code{libwww-perl} becomes @code{perl-libwww}.


@node Java Packages
@subsection Java Packages

@cindex java
Java programs standing for themselves are named as any other package,
using the lowercase upstream name.

To avoid confusion and naming clashes with other programming languages,
it is desirable that the name of a package for a Java package is
prefixed with @code{java-}.  If a project already contains the word
@code{java}, we drop this; for instance, the package @code{ngsjava} is
packaged under the name @code{java-ngs}.

For Java packages containing a single class or a small class hierarchy,
we use the lowercase class name, replace all occurrences of @code{.} by
dashes and prepend the prefix @code{java-}.  So the class
@code{apache.commons.cli} becomes package
@code{java-apache-commons-cli}.


@node Rust Crates
@subsection Rust Crates

@cindex rust
Rust programs standing for themselves are named as any other package, using the
lowercase upstream name.

To prevent namespace collisions we prefix all other Rust packages with the
@code{rust-} prefix.  The name should be changed to lowercase as appropriate and
dashes should remain in place.

In the rust ecosystem it is common for multiple incompatible versions of a
package to be used at any given time, so all package definitions should have a
versioned suffix.  The versioned suffix is the left-most non-zero digit (and
any leading zeros, of course).  This follows the ``caret'' version scheme
intended by Cargo.  Examples@: @code{rust-clap-2}, @code{rust-rand-0.6}.

Because of the difficulty in reusing rust packages as pre-compiled inputs for
other packages the Cargo build system (@pxref{Build Systems,
@code{cargo-build-system}}) presents the @code{#:cargo-inputs} and
@code{cargo-development-inputs} keywords as build system arguments.  It would be
helpful to think of these as similar to @code{propagated-inputs} and
@code{native-inputs}.  Rust @code{dependencies} and @code{build-dependencies}
should go in @code{#:cargo-inputs}, and @code{dev-dependencies} should go in
@code{#:cargo-development-inputs}.  If a Rust package links to other libraries
then the standard placement in @code{inputs} and the like should be used.

Care should be taken to ensure the correct version of dependencies are used; to
this end we try to refrain from skipping the tests or using @code{#:skip-build?}
when possible.  Of course this is not always possible, as the package may be
developed for a different Operating System, depend on features from the Nightly
Rust compiler, or the test suite may have atrophied since it was released.


@node Elm Packages
@subsection Elm Packages

@cindex Elm
Elm applications can be named like other software: their names need not
mention Elm.

Packages in the Elm sense (see @code{elm-build-system} under @ref{Build
Systems}) are required use names of the format
@var{author}@code{/}@var{project}, where both the @var{author} and the
@var{project} may contain hyphens internally, and the @var{author} sometimes
contains uppercase letters.

To form the Guix package name from the upstream name, we follow a convention
similar to Python packages (@pxref{Python Modules}), adding an @code{elm-}
prefix unless the name would already begin with @code{elm-}.

In many cases we can reconstruct an Elm package's upstream name heuristically,
but, since conversion to a Guix-style name involves a loss of information,
this is not always possible.  Care should be taken to add the
@code{'upstream-name} property when necessary so that @samp{guix import elm}
will work correctly (@pxref{Invoking guix import}). The most notable scenarios
when explicitly specifying the upstream name is necessary are:

@enumerate
@item
When the @var{author} is @code{elm} and the @var{project} contains one or more
hyphens, as with @code{elm/virtual-dom}; and

@item
When the @var{author} contains hyphens or uppercase letters, as with
@code{Elm-Canvas/raster-shapes}---unless the @var{author} is
@code{elm-explorations}, which is handled as a special case, so packages like
@code{elm-explorations/markdown} do @emph{not} need to use the
@code{'upstream-name} property.
@end enumerate

The module @code{(guix build-system elm)} provides the following utilities for
working with names and related conventions:

@deffn {Scheme procedure} elm-package-origin @var{elm-name} @var{version} @
  @var{hash}
Returns a Git origin using the repository naming and tagging regime required
for a published Elm package with the upstream name @var{elm-name} at version
@var{version} with sha256 checksum @var{hash}.

For example:
@lisp
(package
  (name "elm-html")
  (version "1.0.0")
  (source
   (elm-package-origin
    "elm/html"
    version
    (base32 "15k1679ja57vvlpinpv06znmrxy09lbhzfkzdc89i01qa8c4gb4a")))
  ...)
@end lisp
@end deffn

@deffn {Scheme procedure} elm->package-name @var{elm-name}
Returns the Guix-style package name for an Elm package with upstream name
@var{elm-name}.

Note that there is more than one possible @var{elm-name} for which
@code{elm->package-name} will produce a given result.
@end deffn

@deffn {Scheme procedure} guix-package->elm-name @var{package}
Given an Elm @var{package}, returns the possibly-inferred upstream name, or
@code{#f} the upstream name is not specified via the @code{'upstream-name}
property and can not be inferred by @code{infer-elm-package-name}.
@end deffn

@deffn {Scheme procedure} infer-elm-package-name @var{guix-name}
Given the @var{guix-name} of an Elm package, returns the inferred upstream
name, or @code{#f} if the upstream name can't be inferred.  If the result is
not @code{#f}, supplying it to @code{elm->package-name} would produce
@var{guix-name}.
@end deffn

@node Fonts
@subsection Fonts

@cindex fonts
For fonts that are in general not installed by a user for typesetting
purposes, or that are distributed as part of a larger software package,
we rely on the general packaging rules for software; for instance, this
applies to the fonts delivered as part of the X.Org system or fonts that
are part of TeX Live.

To make it easier for a user to search for fonts, names for other packages
containing only fonts are constructed as follows, independently of the
upstream package name.

The name of a package containing only one font family starts with
@code{font-}; it is followed by the foundry name and a dash @code{-}
if the foundry is known, and the font family name, in which spaces are
replaced by dashes (and as usual, all upper case letters are transformed
to lower case).
For example, the Gentium font family by SIL is packaged under the name
@code{font-sil-gentium}.

For a package containing several font families, the name of the collection
is used in the place of the font family name.
For instance, the Liberation fonts consist of three families,
Liberation Sans, Liberation Serif and Liberation Mono.
These could be packaged separately under the names
@code{font-liberation-sans} and so on; but as they are distributed together
under a common name, we prefer to package them together as
@code{font-liberation}.

In the case where several formats of the same font family or font collection
are packaged separately, a short form of the format, prepended by a dash,
is added to the package name.  We use @code{-ttf} for TrueType fonts,
@code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
fonts.


@node Coding Style
@section Coding Style

In general our code follows the GNU Coding Standards (@pxref{Top,,,
standards, GNU Coding Standards}).  However, they do not say much about
Scheme, so here are some additional rules.

@menu
* Programming Paradigm::        How to compose your elements.
* Modules::                     Where to store your code?
* Data Types and Pattern Matching::  Implementing data structures.
* Formatting Code::             Writing conventions.
@end menu

@node Programming Paradigm
@subsection Programming Paradigm

Scheme code in Guix is written in a purely functional style.  One
exception is code that involves input/output, and procedures that
implement low-level concepts, such as the @code{memoize} procedure.

@node Modules
@subsection Modules

Guile modules that are meant to be used on the builder side must live in
the @code{(guix build @dots{})} name space.  They must not refer to
other Guix or GNU modules.  However, it is OK for a ``host-side'' module
to use a build-side module.

Modules that deal with the broader GNU system should be in the
@code{(gnu @dots{})} name space rather than @code{(guix @dots{})}.

@node Data Types and Pattern Matching
@subsection Data Types and Pattern Matching

The tendency in classical Lisp is to use lists to represent everything,
and then to browse them ``by hand'' using @code{car}, @code{cdr},
@code{cadr}, and co.  There are several problems with that style,
notably the fact that it is hard to read, error-prone, and a hindrance
to proper type error reports.

Guix code should define appropriate data types (for instance, using
@code{define-record-type*}) rather than abuse lists.  In addition, it
should use pattern matching, via Guile’s @code{(ice-9 match)} module,
especially when matching lists (@pxref{Pattern Matching,,, guile, GNU
Guile Reference Manual}).

@node Formatting Code
@subsection Formatting Code

@cindex formatting code
@cindex coding style
When writing Scheme code, we follow common wisdom among Scheme
programmers.  In general, we follow the
@url{https://mumble.net/~campbell/scheme/style.txt, Riastradh's Lisp
Style Rules}.  This document happens to describe the conventions mostly
used in Guile’s code too.  It is very thoughtful and well written, so
please do read it.

Some special forms introduced in Guix, such as the @code{substitute*}
macro, have special indentation rules.  These are defined in the
@file{.dir-locals.el} file, which Emacs automatically uses.  Also note
that Emacs-Guix provides @code{guix-devel-mode} mode that indents and
highlights Guix code properly (@pxref{Development,,, emacs-guix, The
Emacs-Guix Reference Manual}).

@cindex indentation, of code
@cindex formatting, of code
If you do not use Emacs, please make sure to let your editor knows these
rules.  To automatically indent a package definition, you can also run:

@example
./pre-inst-env guix style @var{package}
@end example

@noindent
@xref{Invoking guix style}, for more information.

@cindex Vim, Scheme code editing
If you are editing code with Vim, we recommend that you run @code{:set
autoindent} so that your code is automatically indented as you type.
Additionally,
@uref{https://www.vim.org/scripts/script.php?script_id=3998,
@code{paredit.vim}} may help you deal with all these parentheses.

We require all top-level procedures to carry a docstring.  This
requirement can be relaxed for simple private procedures in the
@code{(guix build @dots{})} name space, though.

Procedures should not have more than four positional parameters.  Use
keyword parameters for procedures that take more than four parameters.


@node Submitting Patches
@section Submitting Patches

Development is done using the Git distributed version control system.
Thus, access to the repository is not strictly necessary.  We welcome
contributions in the form of patches as produced by @code{git
format-patch} sent to the @email{guix-patches@@gnu.org} mailing list
(@pxref{Submitting patches to a project,,, git, Git User Manual}).
Contributors are encouraged to take a moment to set some Git repository
options (@pxref{Configuring Git}) first, which can improve the
readability of patches.  Seasoned Guix developers may also want to look
at the section on commit access (@pxref{Commit Access}).

This mailing list is backed by a Debbugs instance, which allows us to
keep track of submissions (@pxref{Tracking Bugs and Patches}).  Each
message sent to that mailing list gets a new tracking number assigned;
people can then follow up on the submission by sending email to
@code{@var{ISSUE_NUMBER}@@debbugs.gnu.org}, where @var{ISSUE_NUMBER} is
the tracking number (@pxref{Sending a Patch Series}).

Please write commit logs in the ChangeLog format (@pxref{Change Logs,,,
standards, GNU Coding Standards}); you can check the commit history for
examples.

Before submitting a patch that adds or modifies a package definition,
please run through this check list:

@enumerate
@item
If the authors of the packaged software provide a cryptographic
signature for the release tarball, make an effort to verify the
authenticity of the archive.  For a detached GPG signature file this
would be done with the @code{gpg --verify} command.

@item
Take some time to provide an adequate synopsis and description for the
package.  @xref{Synopses and Descriptions}, for some guidelines.

@item
Run @code{guix lint @var{package}}, where @var{package} is the
name of the new or modified package, and fix any errors it reports
(@pxref{Invoking guix lint}).

@item
Run @code{guix style @var{package}} to format the new package definition
according to the project's conventions (@pxref{Invoking guix style}).

@item
Make sure the package builds on your platform, using @code{guix build
@var{package}}.

@item
We recommend you also try building the package on other supported
platforms.  As you may not have access to actual hardware platforms, we
recommend using the @code{qemu-binfmt-service-type} to emulate them.  In
order to enable it, add the @code{virtualization} service module and the
following service to the list of services in your @code{operating-system}
configuration:

@lisp
(service qemu-binfmt-service-type
 (qemu-binfmt-configuration
   (platforms (lookup-qemu-platforms "arm" "aarch64"))))
@end lisp

Then reconfigure your system.

You can then build packages for different platforms by specifying the
@code{--system} option.  For example, to build the "hello" package for
the armhf or aarch64 architectures, you would run the following
commands, respectively:
@example
guix build --system=armhf-linux --rounds=2 hello
guix build --system=aarch64-linux --rounds=2 hello
@end example

@item
@cindex bundling
Make sure the package does not use bundled copies of software already
available as separate packages.

Sometimes, packages include copies of the source code of their
dependencies as a convenience for users.  However, as a distribution, we
want to make sure that such packages end up using the copy we already
have in the distribution, if there is one.  This improves resource usage
(the dependency is built and stored only once), and allows the
distribution to make transverse changes such as applying security
updates for a given software package in a single place and have them
affect the whole system---something that bundled copies prevent.

@item
Take a look at the profile reported by @command{guix size}
(@pxref{Invoking guix size}).  This will allow you to notice references
to other packages unwillingly retained.  It may also help determine
whether to split the package (@pxref{Packages with Multiple Outputs}),
and which optional dependencies should be used.  In particular, avoid adding
@code{texlive} as a dependency: because of its extreme size, use
the @code{texlive-tiny} package or @code{texlive-union} procedure instead.

@item
For important changes, check that dependent packages (if applicable) are
not affected by the change; @code{guix refresh --list-dependent
@var{package}} will help you do that (@pxref{Invoking guix refresh}).

@c See <https://lists.gnu.org/archive/html/guix-devel/2016-10/msg00933.html>.
@cindex branching strategy
@cindex rebuild scheduling strategy
Depending on the number of dependent packages and thus the amount of
rebuilding induced, commits go to different branches, along these lines:

@table @asis
@item 300 dependent packages or less
@code{master} branch (non-disruptive changes).

@item between 300 and 1,800 dependent packages
@code{staging} branch (non-disruptive changes).  This branch is intended
to be merged in @code{master} every 6 weeks or so.  Topical changes
(e.g., an update of the GNOME stack) can instead go to a specific branch
(say, @code{gnome-updates}).  This branch is not expected to be
buildable or usable until late in its development process.

@item more than 1,800 dependent packages
@code{core-updates} branch (may include major and potentially disruptive
changes).  This branch is intended to be merged in @code{master} every
6 months or so.  This branch is not expected to be buildable or usable
until late in its development process.
@end table

All these branches are @uref{https://@value{SUBSTITUTE-SERVER-1},
tracked by our build farm} and merged into @code{master} once
everything has been successfully built.  This allows us to fix issues
before they hit users, and to reduce the window during which pre-built
binaries are not available.

When we decide to start building the @code{staging} or
@code{core-updates} branches, they will be forked and renamed with the
suffix @code{-frozen}, at which time only bug fixes may be pushed to the
frozen branches.  The @code{core-updates} and @code{staging} branches
will remain open to accept patches for the next cycle.  Please ask on
the mailing list or IRC if unsure where to place a patch.
@c TODO: It would be good with badges on the website that tracks these
@c branches.  Or maybe even a status page.

@item
@cindex determinism, of build processes
@cindex reproducible builds, checking
Check whether the package's build process is deterministic.  This
typically means checking whether an independent build of the package
yields the exact same result that you obtained, bit for bit.

A simple way to do that is by building the same package several times in
a row on your machine (@pxref{Invoking guix build}):

@example
guix build --rounds=2 my-package
@end example

This is enough to catch a class of common non-determinism issues, such
as timestamps or randomly-generated output in the build result.

Another option is to use @command{guix challenge} (@pxref{Invoking guix
challenge}).  You may run it once the package has been committed and
built by @code{@value{SUBSTITUTE-SERVER-1}} to check whether it obtains the same
result as you did.  Better yet: Find another machine that can build it
and run @command{guix publish}.  Since the remote build machine is
likely different from yours, this can catch non-determinism issues
related to the hardware---e.g., use of different instruction set
extensions---or to the operating system kernel---e.g., reliance on
@code{uname} or @file{/proc} files.

@item
When writing documentation, please use gender-neutral wording when
referring to people, such as
@uref{https://en.wikipedia.org/wiki/Singular_they, singular
``they''@comma{} ``their''@comma{} ``them''}, and so forth.

@item
Verify that your patch contains only one set of related changes.
Bundling unrelated changes together makes reviewing harder and slower.

Examples of unrelated changes include the addition of several packages,
or a package update along with fixes to that package.

@item
Please follow our code formatting rules, possibly running
@command{guix style} script to do that automatically for you
(@pxref{Formatting Code}).

@item
When possible, use mirrors in the source URL (@pxref{Invoking guix download}).
Use reliable URLs, not generated ones.  For instance, GitHub archives are not
necessarily identical from one generation to the next, so in this case it's
often better to clone the repository.  Don't use the @command{name} field in
the URL: it is not very useful and if the name changes, the URL will probably
be wrong.

@item
Check if Guix builds (@pxref{Building from Git}) and address the
warnings, especially those about use of undefined symbols.

@item
Make sure your changes do not break Guix and simulate a @code{guix pull} with:
@example
guix pull --url=/path/to/your/checkout --profile=/tmp/guix.master
@end example

@end enumerate

When posting a patch to the mailing list, use @samp{[PATCH] @dots{}} as
a subject, if your patch is to be applied on a branch other than
@code{master}, say @code{core-updates}, specify it in the subject like
@samp{[PATCH core-updates] @dots{}}.

You may use your email client or the @command{git send-email} command
(@pxref{Sending a Patch Series}).  We prefer to get patches in plain
text messages, either inline or as MIME attachments.  You are advised to
pay attention if your email client changes anything like line breaks or
indentation which could potentially break the patches.

Expect some delay when you submit your very first patch to
@email{guix-patches@@gnu.org}. You have to wait until you get an
acknowledgement with the assigned tracking number. Future acknowledgements
should not be delayed.

When a bug is resolved, please close the thread by sending an email to
@email{@var{ISSUE_NUMBER}-done@@debbugs.gnu.org}.

@node Configuring Git
@subsection Configuring Git
@cindex git configuration
@cindex @code{git format-patch}
@cindex @code{git send-email}

If you have not done so already, you may wish to set a name and email
that will be associated with your commits (@pxref{telling git your name,
, Telling Git your name, git, Git User Manual}).  If you wish to use a
different name or email just for commits in this repository, you can
use @command{git config --local}, or edit @file{.git/config} in the
repository instead of @file{~/.gitconfig}.

We provide some default settings in @file{etc/git/gitconfig} which
modify how patches are generated, making them easier to read and apply.
These settings can be applied by manually copying them to
@file{.git/config} in your checkout, or by telling Git to include the
whole file:

@example
git config --local include.path ../etc/git/gitconfig
@end example

From then on, any changes to @file{etc/git/gitconfig} would
automatically take effect.

Since the first patch in a series must be sent separately
(@pxref{Sending a Patch Series}), it can also be helpful to tell
@command{git format-patch} to handle the e-mail threading instead of
@command{git send-email}:

@example
git config --local format.thread shallow
git config --local sendemail.thread no
@end example

@node Sending a Patch Series
@subsection Sending a Patch Series
@cindex patch series
@cindex @code{git send-email}
@cindex @code{git format-patch}

@unnumberedsubsubsec Single Patches
@anchor{Single Patches}
The @command{git send-email} command is the best way to send both single
patches and patch series (@pxref{Multiple Patches}) to the Guix mailing
list.  Sending patches as email attachments may make them difficult to
review in some mail clients, and @command{git diff} does not store commit
metadata.

@quotation Note
The @command{git send-email} command is provided by the @code{send-email}
output of the @code{git} package, i.e. @code{git:send-email}.
@end quotation

The following command will create a patch email from the latest commit,
open it in your @var{EDITOR} or @var{VISUAL} for editing, and send it to
the Guix mailing list to be reviewed and merged:

@example
$ git send-email -1 -a --base=auto --to=guix-patches@@gnu.org
@end example

@quotation Tip
To add a prefix to the subject of your patch, you may use the
@option{--subject-prefix} option.  The Guix project uses this to
specify that the patch is intended for a branch or repository
other than the @code{master} branch of
@url{https://git.savannah.gnu.org/cgit/guix.git}.

@example
git send-email -1 -a --base=auto \
    --subject-prefix='PATCH core-updates' \
    --to=guix-patches@@gnu.org
@end example
@end quotation

The patch email contains a three-dash separator line after the commit
message.  You may ``annotate'' the patch with explanatory text by adding
it under this line.  If you do not wish to annotate the email, you may
drop the @option{-a} flag (which is short for @option{--annotate}).

The @option{--base=auto} flag automatically adds a note at the bottom
of the patch of the commit it was based on, making it easier for
maintainers to rebase and merge your patch.

If you need to send a revised patch, don't resend it like this or send
a ``fix'' patch to be applied on top of the last one; instead, use
@command{git commit -a} or @url{https://git-rebase.io, @command{git rebase}}
to modify the commit, and use the @email{@var{ISSUE_NUMBER}@@debbugs.gnu.org}
address and the @option{-v} flag with @command{git send-email}.

@example
$ git commit -a
$ git send-email -1 -a --base=auto -v @var{REVISION} \
      --to=@var{ISSUE_NUMBER}@@debbugs.gnu.org
@end example

You can find out @var{ISSUE_NUMBER} either by searching on the mumi
interface at @url{issues.guix.gnu.org} for the name of your patch or
reading the acknowledgement email sent automatically by Debbugs in
reply to incoming bugs and patches, which contains the bug number.

@unnumberedsubsubsec Notifying Teams
@anchor{Notifying Teams}
@cindex teams
The @file{etc/teams.scm} script may be used to notify all those who
may be interested in your patch of its existence (@pxref{Teams}).
Use @command{etc/teams.scm list-teams} to display all the teams,
decide which team(s) your patch relates to, and use
@command{etc/teams.scm cc} to output various @command{git send-email}
flags which will notify the appropriate team members, or use
@command{etc/teams.scm cc-members} to detect the appropriate teams
automatically.

@unnumberedsubsubsec Multiple Patches
@anchor{Multiple Patches}
@cindex cover letter
While @command{git send-email} alone will suffice for a single
patch, an unfortunate flaw in Debbugs means you need to be more
careful when sending multiple patches: if you send them all to the
@email{guix-patches@@gnu.org} address, a new issue will be created
for each patch!

When sending a series of patches, it's best to send a Git ``cover
letter'' first, to give reviewers an overview of the patch series.
We can create a directory called @file{outgoing} containing both
our patch series and a cover letter called @file{0000-cover-letter.patch}
with @command{git format-patch}.

@example
$ git format-patch -@var{NUMBER_COMMITS} -o outgoing \
      --cover-letter --base=auto
@end example

We can now send @emph{just} the cover letter to the
@email{guix-patches@@gnu.org} address, which will create an issue
that we can send the rest of the patches to.

@example
$ git send-email outgoing/0000-cover-letter.patch -a \
      --to=guix-patches@@debbugs.gnu.org \
      $(etc/teams.scm cc-members ...)
$ rm outgoing/0000-cover-letter.patch # we don't want to resend it!
@end example

Ensure you edit the email to add an appropriate subject line and
blurb before sending it.  Note the automatically generated shortlog
and diffstat below the blurb.

Once the Debbugs mailer has replied to your cover letter email, you
can send the actual patches to the newly-created issue address.

@example
$ git send-email outgoing/*.patch \
      --to=@var{ISSUE_NUMBER}@@debbugs.gnu.org \
      $(etc/teams.scm cc-members ...)
$ rm -rf outgoing # we don't need these anymore
@end example

Thankfully, this @command{git format-patch} dance is not necessary
to send an amended patch series, since an issue already exists for
the patchset.

@example
$ git send-email -@var{NUMBER_COMMITS} \
      -v@var{REVISION} --base=auto \
      --to @var{ISSUE_NUMBER}@@debbugs.gnu.org
@end example

If need be, you may use @option{--cover-letter -a} to send another cover
letter, e.g. for explaining what's changed since the last revision, and
these changes are necessary.

@node Teams
@subsection Teams
@cindex teams

There are several teams mentoring different parts of the Guix source
code.  To list all those teams, you can run from a Guix checkout:

@example
$ ./etc/teams.scm list-teams
id: mentors
name: Mentors
description: A group of mentors who chaperone contributions by newcomers.
members:
+ Christopher Baines <mail@@cbaines.net>
+ Ricardo Wurmus <rekado@@elephly.net>
+ Mathieu Othacehe <othacehe@@gnu.org>
+ jgart <jgart@@dismail.de>
+ Ludovic Courtès <ludo@@gnu.org>
@dots{}
@end example

You can run the following command to have the @code{Mentors} team put in
CC of a patch series:

@example
$ git send-email --to @var{ISSUE_NUMBER}@@debbugs.gnu.org $(./etc/teams.scm cc mentors) *.patch
@end example

The appropriate team or teams can also be inferred from the modified
files.  For instance, if you want to send the two latest commits of the
current Git repository to review, you can run:

@example
$ guix shell -D guix
[env]$ git send-email --to @var{ISSUE_NUMBER}@@debbugs.gnu.org $(./etc/teams.scm cc-members HEAD~2 HEAD) *.patch
@end example

@node Tracking Bugs and Patches
@section Tracking Bugs and Patches

This section describes how the Guix project tracks its bug reports and
patch submissions.

@menu
* The Issue Tracker::           The official bug and patch tracker.
* Debbugs User Interfaces::     Ways to interact with Debbugs.
* Debbugs Usertags::            Tag reports with custom labels.
@end menu

@node The Issue Tracker
@subsection The Issue Tracker

@cindex bug reports, tracking
@cindex patch submissions, tracking
@cindex issue tracking
@cindex Debbugs, issue tracking system
Bug reports and patch submissions are currently tracked using the
Debbugs instance at @uref{https://bugs.gnu.org}.  Bug reports are filed
against the @code{guix} ``package'' (in Debbugs parlance), by sending
email to @email{bug-guix@@gnu.org}, while patch submissions are filed
against the @code{guix-patches} package by sending email to
@email{guix-patches@@gnu.org} (@pxref{Submitting Patches}).

@node Debbugs User Interfaces
@subsection Debbugs User Interfaces

A web interface (actually @emph{two} web interfaces!) are available to
browse issues:

@itemize
@item
@url{https://issues.guix.gnu.org} provides a pleasant
interface@footnote{The web interface at
@url{https://issues.guix.gnu.org} is powered by Mumi, a nice piece of
software written in Guile, and you can help!  See
@url{https://git.elephly.net/gitweb.cgi?p=software/mumi.git}.} to browse
bug reports and patches, and to participate in discussions;
@item
@url{https://bugs.gnu.org/guix} lists bug reports;
@item
@url{https://bugs.gnu.org/guix-patches} lists patch submissions.
@end itemize

To view discussions related to issue number @var{n}, go to
@indicateurl{https://issues.guix.gnu.org/@var{n}} or
@indicateurl{https://bugs.gnu.org/@var{n}}.

If you use Emacs, you may find it more convenient to interact with
issues using @file{debbugs.el}, which you can install with:

@example
guix install emacs-debbugs
@end example

For example, to list all open issues on @code{guix-patches}, hit:

@example
@kbd{C-u} @kbd{M-x} debbugs-gnu @kbd{RET} @kbd{RET} guix-patches @kbd{RET} n y
@end example

@xref{Top,,, debbugs-ug, Debbugs User Guide}, for more information on
this nifty tool!

@node Debbugs Usertags
@subsection Debbugs Usertags

@cindex usertags, for debbugs
@cindex Debbugs usertags
Debbugs provides a feature called @dfn{usertags} that allows any user to
tag any bug with an arbitrary label.  Bugs can be searched by usertag,
so this is a handy way to organize bugs@footnote{The list of usertags is
public information, and anyone can modify any user's list of usertags,
so keep that in mind if you choose to use this feature.}.

For example, to view all the bug reports (or patches, in the case of
@code{guix-patches}) tagged with the usertag @code{powerpc64le-linux}
for the user @code{guix}, open a URL like the following in a web
browser:
@url{https://debbugs.gnu.org/cgi-bin/pkgreport.cgi?tag=powerpc64le-linux;users=guix}.

For more information on how to use usertags, please refer to the
documentation for Debbugs or the documentation for whatever tool you use
to interact with Debbugs.

In Guix, we are experimenting with usertags to keep track of
architecture-specific issues.  To facilitate collaboration, all our
usertags are associated with the single user @code{guix}.  The following
usertags currently exist for that user:

@table @code

@item powerpc64le-linux
The purpose of this usertag is to make it easy to find the issues that
matter most for the @code{powerpc64le-linux} system type.  Please assign
this usertag to bugs or patches that affect @code{powerpc64le-linux} but
not other system types.  In addition, you may use it to identify issues
that for some reason are particularly important for the
@code{powerpc64le-linux} system type, even if the issue affects other
system types, too.

@item reproducibility
For issues related to reproducibility.  For example, it would be
appropriate to assign this usertag to a bug report for a package that
fails to build reproducibly.

@end table

If you're a committer and you want to add a usertag, just start using it
with the @code{guix} user.  If the usertag proves useful to you,
consider updating this section of the manual so that others will know
what your usertag means.

@node Commit Access
@section Commit Access

@cindex commit access, for developers
Everyone can contribute to Guix without having commit access
(@pxref{Submitting Patches}).  However, for frequent contributors,
having write access to the repository can be convenient.  As a rule of
thumb, a contributor should have accumulated fifty (50) reviewed commits
to be considered as a committer and have sustained their activity in the
project for at least 6 months.  This ensures enough interactions with
the contributor, which is essential for mentoring and assessing whether
they are ready to become a committer.  Commit access should not be
thought of as a ``badge of honor'' but rather as a responsibility a
contributor is willing to take to help the project.

The following sections explain how to get commit access, how to be ready
to push commits, and the policies and community expectations for commits
pushed upstream.

@subsection Applying for Commit Access

When you deem it necessary, consider applying for commit
access by following these steps:

@enumerate
@item
Find three committers who would vouch for you.  You can view the list of
committers at
@url{https://savannah.gnu.org/project/memberlist.php?group=guix}.  Each
of them should email a statement to @email{guix-maintainers@@gnu.org} (a
private alias for the collective of maintainers), signed with their
OpenPGP key.

Committers are expected to have had some interactions with you as a
contributor and to be able to judge whether you are sufficiently
familiar with the project's practices.  It is @emph{not} a judgment on
the value of your work, so a refusal should rather be interpreted as
``let's try again later''.

@item
Send @email{guix-maintainers@@gnu.org} a message stating your intent,
listing the three committers who support your application, signed with
the OpenPGP key you will use to sign commits, and giving its fingerprint
(see below).  See @uref{https://emailselfdefense.fsf.org/en/}, for an
introduction to public-key cryptography with GnuPG.

@c See <https://sha-mbles.github.io/>.
Set up GnuPG such that it never uses the SHA1 hash algorithm for digital
signatures, which is known to be unsafe since 2019, for instance by
adding the following line to @file{~/.gnupg/gpg.conf} (@pxref{GPG
Esoteric Options,,, gnupg, The GNU Privacy Guard Manual}):

@example
digest-algo sha512
@end example

@item
Maintainers ultimately decide whether to grant you commit access,
usually following your referrals' recommendation.

@item
@cindex OpenPGP, signed commits
If and once you've been given access, please send a message to
@email{guix-devel@@gnu.org} to say so, again signed with the OpenPGP key
you will use to sign commits (do that before pushing your first commit).
That way, everyone can notice and ensure you control that OpenPGP key.

@quotation Important
Before you can push for the first time, maintainers must:

@enumerate
@item
add your OpenPGP key to the @code{keyring} branch;
@item
add your OpenPGP fingerprint to the @file{.guix-authorizations} file of
the branch(es) you will commit to.
@end enumerate
@end quotation

@item
Make sure to read the rest of this section and... profit!
@end enumerate

@quotation Note
Maintainers are happy to give commit access to people who have been
contributing for some time and have a track record---don't be shy and
don't underestimate your work!

However, note that the project is working towards a more automated patch
review and merging system, which, as a consequence, may lead us to have
fewer people with commit access to the main repository.  Stay tuned!
@end quotation

All commits that are pushed to the central repository on Savannah must
be signed with an OpenPGP key, and the public key should be uploaded to
your user account on Savannah and to public key servers, such as
@code{keys.openpgp.org}.  To configure Git to automatically sign
commits, run:

@example
git config commit.gpgsign true

# Substitute the fingerprint of your public PGP key.
git config user.signingkey CABBA6EA1DC0FF33
@end example

To check that commits are signed with correct key, use:

@example
make authenticate
@end example

You can prevent yourself from accidentally pushing unsigned or signed
with the wrong key commits to Savannah by using the pre-push Git hook
located at @file{etc/git/pre-push}:

@example
cp etc/git/pre-push .git/hooks/pre-push
@end example

It additionally calls @code{make check-channel-news} to be sure
@file{news.scm} file is correct.

@subsection Commit Policy

If you get commit access, please make sure to follow
the policy below (discussions of the policy can take place on
@email{guix-devel@@gnu.org}).

Non-trivial patches should always be posted to
@email{guix-patches@@gnu.org} (trivial patches include fixing typos,
etc.).  This mailing list fills the patch-tracking database
(@pxref{Tracking Bugs and Patches}).

For patches that just add a new package, and a simple one, it's OK to
commit, if you're confident (which means you successfully built it in a
chroot setup, and have done a reasonable copyright and license
auditing).  Likewise for package upgrades, except upgrades that trigger
a lot of rebuilds (for example, upgrading GnuTLS or GLib).  We have a
mailing list for commit notifications (@email{guix-commits@@gnu.org}),
so people can notice.  Before pushing your changes, make sure to run
@code{git pull --rebase}.

When pushing a commit on behalf of somebody else, please add a
@code{Signed-off-by} line at the end of the commit log message---e.g.,
with @command{git am --signoff}.  This improves tracking of who did
what.

When adding channel news entries (@pxref{Channels, Writing Channel
News}), make sure they are well-formed by running the following command
right before pushing:

@example
make check-channel-news
@end example

For anything else, please post to @email{guix-patches@@gnu.org} and
leave time for a review, without committing anything (@pxref{Submitting
Patches}).  If you didn’t receive any reply after two weeks, and if
you're confident, it's OK to commit.

That last part is subject to being adjusted, allowing individuals to commit
directly on non-controversial changes on parts they’re familiar with.

@subsection Addressing Issues

Peer review (@pxref{Submitting Patches}) and tools such as
@command{guix lint} (@pxref{Invoking guix lint}) and the test suite
(@pxref{Running the Test Suite}) should catch issues before they are
pushed.  Yet, commits that ``break'' functionality might occasionally
go through.  When that happens, there are two priorities: mitigating
the impact, and understanding what happened to reduce the chance of
similar incidents in the future.  The responsibility for both these
things primarily lies with those involved, but like everything this is
a group effort.

Some issues can directly affect all users---for instance because they
make @command{guix pull} fail or break core functionality, because they
break major packages (at build time or run time), or because they
introduce known security vulnerabilities.

@cindex reverting commits
The people involved in authoring, reviewing, and pushing such
commit(s) should be at the forefront to mitigate their impact in a
timely fashion: by pushing a followup commit to fix it (if possible),
or by reverting it to leave time to come up with a proper fix, and by
communicating with other developers about the problem.

If these persons are unavailable to address the issue in time, other
committers are entitled to revert the commit(s), explaining in the
commit log and on the mailing list what the problem was, with the goal
of leaving time to the original committer, reviewer(s), and author(s)
to propose a way forward.

Once the problem has been dealt with, it is the responsibility of
those involved to make sure the situation is understood.  If you are
working to understand what happened, focus on gathering information
and avoid assigning any blame.  Do ask those involved to describe what
happened, do not ask them to explain the situation---this would
implicitly blame them, which is unhelpful.  Accountability comes from
a consensus about the problem, learning from it and improving
processes so that it's less likely to reoccur.

@subsection Commit Revocation

In order to reduce the possibility of mistakes, committers will have
their Savannah account removed from the Guix Savannah project and their
key removed from @file{.guix-authorizations} after 12 months of
inactivity; they can ask to regain commit access by emailing the
maintainers, without going through the vouching process.

Maintainers@footnote{See @uref{https://guix.gnu.org/en/about} for the
current list of maintainers.  You can email them privately at
@email{guix-maintainers@@gnu.org}.} may also revoke an individual's
commit rights, as a last resort, if cooperation with the rest of the
community has caused too much friction---even within the bounds of the
project's code of conduct (@pxref{Contributing}).  They would only do so
after public or private discussion with the individual and a clear
notice.  Examples of behavior that hinders cooperation and could lead to
such a decision include:

@itemize
@item repeated violation of the commit policy stated above;
@item repeated failure to take peer criticism into account;
@item breaching trust through a series of grave incidents.
@end itemize

When maintainers resort to such a decision, they notify developers on
@email{guix-devel@@gnu.org}; inquiries may be sent to
@email{guix-maintainers@@gnu.org}.  Depending on the situation, the
individual may still be welcome to contribute.

@subsection Helping Out

One last thing: the project keeps moving forward because committers not
only push their own awesome changes, but also offer some of their time
@emph{reviewing} and pushing other people's changes.  As a committer,
you're welcome to use your expertise and commit rights to help other
contributors, too!

@node Updating the Guix Package
@section Updating the Guix Package

@cindex update-guix-package, updating the guix package
It is sometimes desirable to update the @code{guix} package itself (the
package defined in @code{(gnu packages package-management)}), for
example to make new daemon features available for use by the
@code{guix-service-type} service type.  In order to simplify this task,
the following command can be used:

@example
make update-guix-package
@end example

The @code{update-guix-package} make target will use the last known
@emph{commit} corresponding to @code{HEAD} in your Guix checkout,
compute the hash of the Guix sources corresponding to that commit and
update the @code{commit}, @code{revision} and hash of the @code{guix}
package definition.

To validate that the updated @code{guix} package hashes are correct and
that it can be built successfully, the following command can be run from
the directory of your Guix checkout:

@example
./pre-inst-env guix build guix
@end example

To guard against accidentally updating the @code{guix} package to a
commit that others can't refer to, a check is made that the commit used
has already been pushed to the Savannah-hosted Guix git repository.

This check can be disabled, @emph{at your own peril}, by setting the
@code{GUIX_ALLOW_ME_TO_USE_PRIVATE_COMMIT} environment variable.  When
this variable is set, the updated package source is also added to the
store.  This is used as part of the release process of Guix.

@cindex documentation
@node Writing Documentation
@section Writing Documentation

Guix is documented using the Texinfo system.  If you are not yet
familiar with it, we accept contributions for documentation in most
formats.  That includes plain text, Markdown, Org, etc.

Documentation contributions can be sent to
@email{guix-patches@@gnu.org}.  Prepend @samp{[DOCUMENTATION]} to the
subject.

When you need to make more than a simple addition to the documentation,
we prefer that you send a proper patch as opposed to sending an email
as described above.  @xref{Submitting Patches} for more information on
how to send your patches.

To modify the documentation, you need to edit @file{doc/guix.texi} and
@file{doc/contributing.texi} (which contains this documentation
section), or @file{doc/guix-cookbook.texi} for the cookbook.  If
you compiled the Guix repository before, you will have
many more @file{.texi} files that are translations of these
documents.  Do not modify them, the translation is managed through
@uref{https://translate.fedoraproject.org/projects/guix, Weblate}.
@xref{Translating Guix} for more information.

To render documentation, you must first make sure that you ran
@command{./configure} in your source tree (@pxref{Running Guix Before
It Is Installed}).  After that you can run one of the following
commands:

@itemize
@item @samp{make doc/guix.info} to compile the Info manual.
      You can check it with @command{info doc/guix.info}.
@item @samp{make doc/guix.html} to compile the HTML version.
      You can point your browser to the relevant file in the
      @file{doc/guix.html} directory.
@item @samp{make doc/guix-cookbook.info} for the cookbook Info manual.
@item @samp{make doc/guix-cookbook.html} for the cookbook HTML version.
@end itemize

@cindex translation
@cindex l10n
@cindex i18n
@cindex native language support
@node Translating Guix
@section Translating Guix

Writing code and packages is not the only way to provide a meaningful
contribution to Guix.  Translating to a language you speak is another
example of a valuable contribution you can make.  This section is designed
to describe the translation process.  It gives you advice on how you can
get involved, what can be translated, what mistakes you should avoid and
what we can do to help you!

Guix is a big project that has multiple components that can be translated.
We coordinate the translation effort on a
@uref{https://translate.fedoraproject.org/projects/guix/,Weblate instance}
hosted by our friends at Fedora.  You will need an account to submit
translations.

Some of the software packaged in Guix also contain translations.  We do not
host a translation platform for them.  If you want to translate a package
provided by Guix, you should contact their developers or find the information
on their website.  As an example, you can find the homepage of the
@code{hello} package by typing @code{guix show hello}.  On the ``homepage''
line, you will see @url{https://www.gnu.org/software/hello/} as the homepage.

Many GNU and non-GNU packages can be translated on the
@uref{https://translationproject.org,Translation Project}.  Some projects
with multiple components have their own platform.  For instance, GNOME has
its own platform, @uref{https://l10n.gnome.org/,Damned Lies}.

Guix has five components hosted on Weblate.

@itemize
@item @code{guix} contains all the strings from the Guix software (the
      guided system installer, the package manager, etc), excluding packages.
@item @code{packages} contains the synopsis (single-sentence description
      of a package) and description (longer description) of packages in Guix.
@item @code{website} contains the official Guix website, except for
      blog posts and multimedia content.
@item @code{documentation-manual} corresponds to this manual.
@item @code{documentation-cookbook} is the component for the cookbook.
@end itemize

@subsubheading General Directions

Once you get an account, you should be able to select a component from
@uref{https://translate.fedoraproject.org/projects/guix/,the guix project},
and select a language.  If your language does not appear in the list, go
to the bottom and click on the ``Start new translation'' button.  Select
the language you want to translate to from the list, to start your new
translation.

Like lots of other free software packages, Guix uses
@uref{https://www.gnu.org/software/gettext,GNU Gettext} for its translations,
with which translatable strings are extracted from the source code to so-called
PO files.

Even though PO files are text files, changes should not be made with a text
editor but with PO editing software.  Weblate integrates PO editing
functionality.  Alternatively, translators can use any of various
free-software tools for filling in translations, of which
@uref{https://poedit.net/,Poedit} is one example, and (after logging in)
@uref{https://docs.weblate.org/en/latest/user/files.html,upload} the changed
file.  There is also a special
@uref{https://www.emacswiki.org/emacs/PoMode,PO editing mode} for users of GNU
Emacs.  Over time translators find out what software they are happy with and
what features they need.

On Weblate, you will find various links to the editor, that will show various
subsets (or all) of the strings.  Have a look around and at the
@uref{https://docs.weblate.org/en/latest/,documentation} to familiarize
yourself with the platform.

@subsubheading Translation Components

In this section, we provide more detailed guidance on the translation
process, as well as details on what you should or should not do.  When in
doubt, please contact us, we will be happy to help!

@table @asis
@item guix
Guix is written in the Guile programming language, and some strings contain
special formatting that is interpreted by Guile.  These special formatting
should be highlighted by Weblate.  They start with @code{~} followed by one
or more characters.

When printing the string, Guile replaces the special formatting symbols with
actual values.  For instance, the string @samp{ambiguous package specification
`~a'} would be substituted to contain said package specification instead of
@code{~a}.  To properly translate this string, you must keep the formatting
code in your translation, although you can place it where it makes sense in
your language.  For instance, the French translation says @samp{spécification
du paquet « ~a » ambiguë} because the adjective needs to be placed in the
end of the sentence.

If there are multiple formatting symbols, make sure to respect the order.
Guile does not know in which order you intended the string to be read, so it
will substitute the symbols in the same order as the English sentence.

As an example, you cannot translate @samp{package '~a' has been superseded by
'~a'} by @samp{'~a' superseeds package '~a'}, because the meaning would be
reversed.  If @var{foo} is superseded by @var{bar}, the translation would read
@samp{'foo' superseeds package 'bar'}.  To work around this problem, it
is possible to use more advanced formatting to select a given piece of data,
instead of following the default English order.  @xref{Formatted Output,,,
guile, GNU Guile Reference Manual}, for more information on formatting in Guile.

@item packages

Package descriptions occasionally contain Texinfo markup (@pxref{Synopses
and Descriptions}).   Texinfo markup looks like @samp{@@code@{rm -rf@}},
@samp{@@emph@{important@}}, etc.  When translating, please leave markup as is.

The characters after ``@@'' form the name of the markup, and the text between
``@{'' and ``@}'' is its content.  In general, you should not translate the
content of markup like @code{@@code}, as it contains literal code that do not
change with language.  You can translate the content of formatting markup such
as @code{@@emph}, @code{@@i}, @code{@@itemize}, @code{@@item}.  However, do
not translate the name of the markup, or it will not be recognized.  Do
not translate the word after @code{@@end}, it is the name of the markup that
is closed at this position (e.g.@: @code{@@itemize ... @@end itemize}).

@item documentation-manual and documentation-cookbook

The first step to ensure a successful translation of the manual is to find
and translate the following strings @emph{first}:

@itemize
@item @code{version.texi}: Translate this string as @code{version-xx.texi},
      where @code{xx} is your language code (the one shown in the URL on
      weblate).
@item @code{contributing.texi}: Translate this string as
      @code{contributing.xx.texi}, where @code{xx} is the same language code.
@item @code{Top}: Do not translate this string, it is important for Texinfo.
      If you translate it, the document will be empty (missing a Top node).
      Please look for it, and register @code{Top} as its translation.
@end itemize

Translating these strings first ensure we can include your translation in
the guix repository without breaking the make process or the
@command{guix pull} machinery.

The manual and the cookbook both use Texinfo.  As for @code{packages}, please
keep Texinfo markup as is.  There are more possible markup types in the manual
than in the package descriptions.  In general, do not translate the content
of @code{@@code}, @code{@@file}, @code{@@var}, @code{@@value}, etc.  You
should translate the content of formatting markup such as @code{@@emph},
@code{@@i}, etc.

The manual contains sections that can be referred to by name by @code{@@ref},
@code{@@xref} and @code{@@pxref}.  We have a mechanism in place so you do
not have to translate their content.  If you keep the English title, we will
automatically replace it with your translation of that title.  This ensures
that Texinfo will always be able to find the node. If you decide to change
the translation of the title, the references will automatically be updated
and you will not have to update them all yourself.

When translating references from the cookbook to the manual, you need to
replace the name of the manual and the name of the section.  For instance,
to translate @code{@@pxref@{Defining Packages,,, guix, GNU Guix Reference
Manual@}}, you would replace @code{Defining Packages} with the title of that
section in the translated manual @emph{only} if that title is translated.
If the title is not translated in your language yet, do not translate it here,
or the link will be broken.  Replace @code{guix} with @code{guix.xx} where
@code{xx} is your language code.  @code{GNU Guix Reference Manual} is the
text of the link.  You can translate it however you wish.

@item website

The website pages are written using SXML, an s-expression version of HTML,
the basic language of the web.  We have a process to extract translatable
strings from the source, and replace complex s-expressions with a more familiar
XML markup, where each markup is numbered.  Translators can arbitrarily change
the ordering, as in the following example.

@example
#. TRANSLATORS: Defining Packages is a section name
#. in the English (en) manual.
#: apps/base/templates/about.scm:64
msgid "Packages are <1>defined<1.1>en</1.1><1.2>Defining-Packages.html</1.2></1> as native <2>Guile</2> modules."
msgstr "Pakete werden als reine <2>Guile</2>-Module <1>definiert<1.1>de</1.1><1.2>Pakete-definieren.html</1.2></1>."
@end example

Note that you need to include the same markups.  You cannot skip any.
@end table

In case you make a mistake, the component might fail to build properly with your
language, or even make guix pull fail.  To prevent that, we have a process
in place to check the content of the files before pushing to our repository.
We will not be able to update the translation for your language in Guix, so
we will notify you (through weblate and/or by email) so you get a chance to
fix the issue.

@subsubheading Outside of Weblate

Currently, some parts of Guix cannot be translated on Weblate, help wanted!

@itemize
@item @command{guix pull} news can be translated in @file{news.scm}, but is not
      available from Weblate.  If you want to provide a translation, you
      can prepare a patch as described above, or simply send us your
      translation with the name of the news entry you translated and your
      language. @xref{Writing Channel News}, for more information about
      channel news.
@item Guix blog posts cannot currently be translated.
@item The installer script (for foreign distributions) is entirely in English.
@item Some of the libraries Guix uses cannot be translated or are translated
      outside of the Guix project.  Guile itself is not internationalized.
@item Other manuals linked from this manual or the cookbook might not be
      translated.
@end itemize

@subsubheading Conditions for Inclusion

There are no conditions for adding new translations of the @code{guix} and
@code{guix-packages} components, other than they need at least one translated
string.  New languages will be added to Guix as soon as possible.  The
files may be removed if they fall out of sync and have no more translated
strings.

Given that the web site is dedicated to new users, we want its translation
to be as complete as possible before we include it in the language menu.
For a new language to be included, it needs to reach at least 80% completion.
When a language is included, it may be removed in the future if it stays
out of sync and falls below 60% completion.

The manual and cookbook are automatically added in the default compilation
target.  Every time we synchronize translations, developers need to
recompile all the translated manuals and cookbooks.  This is useless for what
is essentially the English manual or cookbook.  Therefore, we will only
include a new language when it reaches 10% completion in the component.
When a language is included, it may be removed in the future if it stays
out of sync and falls below 5% completion.

@subsubheading Translation Infrastructure

Weblate is backed by a git repository from which it discovers new strings to
translate and pushes new and updated translations.  Normally, it would be
enough to give it commit access to our repositories.  However, we decided
to use a separate repository for two reasons.  First, we would have to give
Weblate commit access and authorize its signing key, but we do not trust it
in the same way we trust guix developers, especially since we do not manage
the instance ourselves.  Second, if translators mess something up, it can
break the generation of the website and/or guix pull for all our users,
independently of their language.

For these reasons, we use a dedicated repository to host translations, and we
synchronize it with our guix and artworks repositories after checking no issue
was introduced in the translation.

Developers can download the latest PO files from weblate in the Guix
repository by running the @command{make download-po} command.  It will
automatically download the latest files from weblate, reformat them to a
canonical form, and check they do not contain issues.  The manual needs to be
built again to check for additional issues that might crash Texinfo.

Before pushing new translation files, developers should add them to the
make machinery so the translations are actually available.  The process
differs for the various components.

@itemize
@item New po files for the @code{guix} and @code{packages} components must
      be registered by adding the new language to @file{po/guix/LINGUAS} or
      @file{po/packages/LINGUAS}.
@item New po files for the @code{documentation-manual} component must be
      registered by adding the file name to @code{DOC_PO_FILES} in
      @file{po/doc/local.mk}, the generated @file{%D%/guix.xx.texi} manual to
      @code{info_TEXINFOS} in @file{doc/local.mk} and the generated
      @file{%D%/guix.xx.texi} and @file{%D%/contributing.xx.texi} to
      @code{TRANSLATED_INFO} also in @file{doc/local.mk}.
@item New po files for the @code{documentation-cookbook} component must be
      registered by adding the file name to @code{DOC_COOKBOOK_PO_FILES} in
      @file{po/doc/local.mk}, the generated @file{%D%/guix-cookbook.xx.texi}
      manual to @code{info_TEXINFOS} in @file{doc/local.mk} and the generated
      @file{%D%/guix-cookbook.xx.texi} to @code{TRANSLATED_INFO} also
      in @file{doc/local.mk}.
@item New po files for the @code{website} component must be added to the
      @code{guix-artwork} repository, in @file{website/po/}.
      @file{website/po/LINGUAS} and @file{website/po/ietf-tags.scm} must
      be updated accordingly (see @file{website/i18n-howto.txt} for more
      information on the process).
@end itemize