diff options
| -rw-r--r-- | Makefile.am | 1 | ||||
| -rw-r--r-- | doc/guix.texi | 27 | ||||
| -rw-r--r-- | guix.scm | 1 | ||||
| -rw-r--r-- | guix/monad-repl.scm | 81 |
4 files changed, 110 insertions, 0 deletions
diff --git a/Makefile.am b/Makefile.am index eab126acee..17a676ac54 100644 --- a/Makefile.am +++ b/Makefile.am @@ -37,6 +37,7 @@ MODULES = \ guix/download.scm \ guix/git-download.scm \ guix/monads.scm \ + guix/monad-repl.scm \ guix/gexp.scm \ guix/profiles.scm \ guix/serialization.scm \ diff --git a/doc/guix.texi b/doc/guix.texi index a4ffa8524b..92eccad118 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -1937,6 +1937,33 @@ effect, one must use @code{run-with-store}: @result{} /gnu/store/...-profile.sh @end example +Note that the @code{(guix monad-repl)} module extends Guile's REPL with +new ``meta-commands'' to make it easier to deal with monadic procedures: +@code{run-in-store}, and @code{enter-store-monad}. The former, is used +to ``run'' a single monadic value through the store: + +@example +scheme@@(guile-user)> ,run-in-store (package->derivation hello) +$1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}> +@end example + +The latter enters a recursive REPL, where all the return values are +automatically run through the store: + +@example +scheme@@(guile-user)> ,enter-store-monad +store-monad@@(guile-user) [1]> (package->derivation hello) +$2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}> +store-monad@@(guile-user) [1]> (text-file "foo" "Hello!") +$3 = "/gnu/store/@dots{}-foo" +store-monad@@(guile-user) [1]> ,q +scheme@@(guile-user)> +@end example + +@noindent +Note that non-monadic values cannot be returned in the +@code{store-monad} REPL. + The main syntactic forms to deal with monads in general are described below. diff --git a/guix.scm b/guix.scm index 706ea29065..8753c21e42 100644 --- a/guix.scm +++ b/guix.scm @@ -30,6 +30,7 @@ ftp-client gexp monads + monad-repl packages store utils)) diff --git a/guix/monad-repl.scm b/guix/monad-repl.scm new file mode 100644 index 0000000000..5242f5448b --- /dev/null +++ b/guix/monad-repl.scm @@ -0,0 +1,81 @@ +;;; GNU Guix --- Functional package management for GNU +;;; Copyright © 2014 Ludovic Courtès <ludo@gnu.org> +;;; +;;; This file is part of GNU Guix. +;;; +;;; GNU Guix is free software; you can redistribute it and/or modify it +;;; under the terms of the GNU General Public License as published by +;;; the Free Software Foundation; either version 3 of the License, or (at +;;; your option) any later version. +;;; +;;; GNU Guix is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;;; GNU General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. + +(define-module (guix monad-repl) + #:use-module (guix store) + #:use-module (guix monads) + #:use-module (ice-9 pretty-print) + #:use-module (system repl repl) + #:use-module (system repl common) + #:use-module (system repl command) + #:use-module (system base language) + #:use-module (system base compile) + #:use-module (srfi srfi-26) + #:export (run-in-store + enter-store-monad)) + +;;; Comment: +;;; +;;; This modules provides a couple of REPL meta-commands that make it easier +;;; to work with monadic procedures in the store monad. +;;; +;;; Code: + +(define* (monad-language monad run #:optional (name 'monad)) + "Return a language with a special evaluator that causes monadic values + to be \"run\" in MONAD using procedure RUN." + (let ((scheme (lookup-language 'scheme))) + (define (evaluate-monadic-expression exp env) + (let ((mvalue (compile exp #:to 'value #:env env))) + (run mvalue))) + + (make-language #:name name + #:title "Monad" + #:reader (language-reader scheme) + #:compilers (language-compilers scheme) + #:decompilers (language-decompilers scheme) + #:evaluator evaluate-monadic-expression + #:printer (language-printer scheme) + #:make-default-environment + (language-make-default-environment scheme)))) + +(define (store-monad-language) + "Return a compiler language for the store monad." + (let ((store (open-connection))) + (monad-language %store-monad + (cut run-with-store store <>) + 'store-monad))) + +(define-meta-command ((run-in-store guix) repl (form)) + "run-in-store EXP +Run EXP through the store monad." + (let ((value (with-store store + (run-with-store store (repl-eval repl form))))) + (run-hook before-print-hook value) + (pretty-print value))) + +(define-meta-command ((enter-store-monad guix) repl) + "enter-store-monad +Enter a REPL for values in the store monad." + (let ((new (make-repl (store-monad-language)))) + ;; Force interpretation so that our specially-crafted language evaluator + ;; is actually used. + (repl-option-set! new 'interp #t) + (run-repl new))) + +;;; monad-repl.scm ends here |