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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013 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 (test-monads)
#:use-module (guix store)
#:use-module (guix monads)
#:use-module (guix derivations)
#:use-module ((guix packages)
#:select (package-derivation %current-system))
#:use-module (gnu packages)
#:use-module (gnu packages bootstrap)
#:use-module (ice-9 match)
#:use-module (rnrs io ports)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-64))
;; Test the (guix store) module.
(define %store
(open-connection))
;; Make sure we build everything by ourselves.
(set-build-options %store #:use-substitutes? #f)
(define %monads
(list %identity-monad %store-monad))
(define %monad-run
(list identity
(cut run-with-store %store <>)))
(test-begin "monads")
(test-assert "monad?"
(and (every monad? %monads)
(every (compose procedure? monad-bind) %monads)
(every (compose procedure? monad-return) %monads)))
;; The 3 "monad laws": <http://www.haskell.org/haskellwiki/Monad_laws>.
(test-assert "left identity"
(every (lambda (monad run)
(let ((number (random 777)))
(with-monad monad
(define (f x)
(return (* (1+ number) 2)))
(= (run (>>= (return number) f))
(run (f number))))))
%monads
%monad-run))
(test-assert "right identity"
(every (lambda (monad run)
(with-monad monad
(let ((number (return (random 777))))
(= (run (>>= number return))
(run number)))))
%monads
%monad-run))
(test-assert "associativity"
(every (lambda (monad run)
(with-monad monad
(define (f x)
(return (+ 1 x)))
(define (g x)
(return (* 2 x)))
(let ((number (return (random 777))))
(= (run (>>= (>>= number f) g))
(run (>>= number (lambda (x) (>>= (f x) g))))))))
%monads
%monad-run))
(test-assert "lift"
(every (lambda (monad run)
(let ((f (lift1 1+ monad)))
(with-monad monad
(let ((number (random 777)))
(= (run (>>= (return number) f))
(1+ number))))))
%monads
%monad-run))
(test-assert "mlet* + text-file + package-file"
(run-with-store %store
(mlet* %store-monad ((guile (package-file %bootstrap-guile "bin/guile"))
(file (text-file "monadic" guile)))
(return (equal? (call-with-input-file file get-string-all)
guile)))
#:guile-for-build (package-derivation %store %bootstrap-guile)))
(test-assert "mlet* + derivation-expression"
(run-with-store %store
(mlet* %store-monad ((guile (package-file %bootstrap-guile "bin/guile"))
(gdrv (package->derivation %bootstrap-guile))
(exp -> `(let ((out (assoc-ref %outputs "out")))
(mkdir out)
(symlink ,guile
(string-append out "/guile-rocks"))))
(drv (derivation-expression "rocks" exp
#:inputs
`(("g" ,gdrv))))
(out -> (derivation->output-path drv))
(built? (built-derivations (list drv))))
(return (and built?
(equal? guile
(readlink (string-append out "/guile-rocks"))))))
#:guile-for-build (package-derivation %store %bootstrap-guile)))
(test-assert "mapm"
(every (lambda (monad run)
(with-monad monad
(equal? (run (mapm monad (lift1 1+ monad) (map return (iota 10))))
(map 1+ (iota 10)))))
%monads
%monad-run))
(test-assert "sequence"
(every (lambda (monad run)
(let* ((input (iota 100))
(order '()))
(define (frob i)
;; The side effect here is used to keep track of the order in
;; which monadic values are bound.
(set! order (cons i order))
i)
(and (equal? input
(run (sequence monad
(map (lift1 frob monad) input))))
;; Make sure this is from left to right.
(equal? order (reverse input)))))
%monads
%monad-run))
(test-assert "listm"
(every (lambda (monad run)
(run (with-monad monad
(let ((lst (listm monad
(return 1) (return 2) (return 3))))
(mlet monad ((lst lst))
(return (equal? '(1 2 3) lst)))))))
%monads
%monad-run))
(test-assert "anym"
(every (lambda (monad run)
(eq? (run (with-monad monad
(let ((lst (list (return 1) (return 2) (return 3))))
(anym monad
(lambda (x)
(and (odd? x) 'odd!))
lst))))
'odd!))
%monads
%monad-run))
(test-end "monads")
(exit (= (test-runner-fail-count (test-runner-current)) 0))
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