751630c9c3
Suggested by Federico Beffa <beffa@fbengineering.ch>.
* guix/monads.scm (bind-syntax): New macro.
(with-monad): Use it instead of 'identifier-syntax'.
* tests/monads.scm (">>= with more than two arguments"): New test.
* doc/guix.texi (The Store Monad): Explain that there can be several MPROC.
Add an example.
257 lines
8.7 KiB
Scheme
257 lines
8.7 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (test-monads)
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#:use-module (guix tests)
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#:use-module (guix store)
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#:use-module (guix monads)
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#:use-module (guix derivations)
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#:use-module (guix packages)
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#:use-module (gnu packages)
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#:use-module (gnu packages bootstrap)
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#:use-module ((gnu packages base) #:select (coreutils))
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#:use-module (ice-9 match)
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#:use-module (rnrs io ports)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-26)
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#:use-module (srfi srfi-64))
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;; Test the (guix monads) module.
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(define %store
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(open-connection-for-tests))
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(define %monads
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(list %identity-monad %store-monad %state-monad))
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(define %monad-run
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(list identity
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(cut run-with-store %store <>)
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(cut run-with-state <> '())))
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(define-syntax-rule (values->list exp)
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(call-with-values (lambda () exp)
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list))
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(test-begin "monads")
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(test-assert "monad?"
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(and (every monad? %monads)
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(every (compose procedure? monad-bind) %monads)
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(every (compose procedure? monad-return) %monads)))
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;; The 3 "monad laws": <http://www.haskell.org/haskellwiki/Monad_laws>.
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(test-assert "left identity"
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(every (lambda (monad run)
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(let ((number (random 777)))
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(with-monad monad
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(define (f x)
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(return (* (1+ number) 2)))
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(= (run (>>= (return number) f))
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(run (f number))))))
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%monads
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%monad-run))
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(test-assert "right identity"
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(every (lambda (monad run)
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(with-monad monad
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(let ((number (return (random 777))))
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(= (run (>>= number return))
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(run number)))))
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%monads
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%monad-run))
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(test-assert "associativity"
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(every (lambda (monad run)
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(with-monad monad
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(define (f x)
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(return (+ 1 x)))
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(define (g x)
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(return (* 2 x)))
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(let ((number (return (random 777))))
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(= (run (>>= (>>= number f) g))
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(run (>>= number (lambda (x) (>>= (f x) g))))))))
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%monads
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%monad-run))
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(test-assert "lift"
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(every (lambda (monad run)
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(let ((f (lift1 1+ monad)))
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(with-monad monad
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(let ((number (random 777)))
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(= (run (>>= (return number) f))
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(1+ number))))))
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%monads
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%monad-run))
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(test-assert ">>= with more than two arguments"
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(every (lambda (monad run)
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(let ((1+ (lift1 1+ monad))
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(2* (lift1 (cut * 2 <>) monad)))
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(with-monad monad
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(let ((number (random 777)))
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(= (run (>>= (return number)
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1+ 1+ 1+
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2* 2* 2*))
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(* 8 (+ number 3)))))))
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%monads
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%monad-run))
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(test-assert "mbegin"
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(every (lambda (monad run)
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(with-monad monad
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(let* ((been-there? #f)
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(number (mbegin monad
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(return 1)
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(begin
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(set! been-there? #t)
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(return 2))
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(return 3))))
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(and (= (run number) 3)
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been-there?))))
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%monads
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%monad-run))
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(test-assert "mlet* + text-file + package-file"
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(run-with-store %store
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(mlet* %store-monad ((guile (package-file %bootstrap-guile "bin/guile"))
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(file (text-file "monadic" guile)))
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(return (equal? (call-with-input-file file get-string-all)
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guile)))
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#:guile-for-build (package-derivation %store %bootstrap-guile)))
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(test-assert "package-file, default system"
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;; The default system should be the one at '>>=' time, not the one at
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;; invocation time. See <http://bugs.gnu.org/18002>.
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(run-with-store %store
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(mlet* %store-monad
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((system -> (%current-system))
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(file (parameterize ((%current-system "foobar64-linux"))
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(package-file coreutils "bin/ls")))
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(cu (package->derivation coreutils)))
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(return (string=? file
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(string-append (derivation->output-path cu)
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"/bin/ls"))))
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#:guile-for-build (package-derivation %store %bootstrap-guile)))
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(test-assert "package-file + package->cross-derivation"
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(run-with-store %store
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(mlet* %store-monad ((target -> "mips64el-linux-gnu")
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(file (package-file coreutils "bin/ls"
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#:target target))
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(xcu (package->cross-derivation coreutils target)))
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(let ((output (derivation->output-path xcu)))
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(return (string=? file (string-append output "/bin/ls")))))
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#:guile-for-build (package-derivation %store %bootstrap-guile)))
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(test-assert "interned-file"
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(run-with-store %store
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(mlet* %store-monad ((file -> (search-path %load-path "guix.scm"))
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(a (interned-file file))
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(b (interned-file file "b")))
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(return (equal? (call-with-input-file file get-string-all)
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(call-with-input-file a get-string-all)
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(call-with-input-file b get-string-all))))
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#:guile-for-build (package-derivation %store %bootstrap-guile)))
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(test-assert "mapm"
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(every (lambda (monad run)
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(with-monad monad
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(equal? (run (mapm monad (lift1 1+ monad) (iota 10)))
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(map 1+ (iota 10)))))
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%monads
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%monad-run))
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(test-assert "sequence"
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(every (lambda (monad run)
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(let* ((input (iota 100))
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(order '()))
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(define (frob i)
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(mlet monad ((foo (return 'foo)))
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;; The side effect here is used to keep track of the order in
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;; which monadic values are bound. Perform the side effect
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;; within a '>>=' so that it is performed when the return
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;; value is actually bound.
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(set! order (cons i order))
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(return i)))
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(and (equal? input
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(run (sequence monad (map frob input))))
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;; Make sure this is from left to right.
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(equal? order (reverse input)))))
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%monads
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%monad-run))
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(test-assert "listm"
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(every (lambda (monad run)
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(run (with-monad monad
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(let ((lst (listm monad
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(return 1) (return 2) (return 3))))
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(mlet monad ((lst lst))
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(return (equal? '(1 2 3) lst)))))))
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%monads
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%monad-run))
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(test-assert "anym"
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(every (lambda (monad run)
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(eq? (run (with-monad monad
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(anym monad
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(lift1 (lambda (x)
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(and (odd? x) 'odd!))
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monad)
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(append (make-list 1000 0)
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(list 1 2)))))
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'odd!))
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%monads
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%monad-run))
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(test-equal "set-current-state"
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(list '(a a d) 'd)
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(values->list
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(run-with-state
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(mlet* %state-monad ((init (current-state))
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(init2 (set-current-state 'b)))
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(mbegin %state-monad
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(set-current-state 'c)
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(set-current-state 'd)
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(mlet %state-monad ((last (current-state)))
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(return (list init init2 last)))))
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'a)))
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(test-equal "state-push etc."
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(list '((z . 2) (p . (1)) (a . (1))) '(2 1))
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(values->list
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(run-with-state
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(mbegin %state-monad
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(state-push 1) ;(1)
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(state-push 2) ;(2 1)
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(mlet* %state-monad ((z (state-pop)) ;(1)
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(p (current-state))
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(a (state-push z))) ;(2 1)
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(return `((z . ,z) (p . ,p) (a . ,a)))))
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'())))
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(test-end "monads")
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(exit (= (test-runner-fail-count (test-runner-current)) 0))
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