;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016, 2022 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 tests)
#:use-module (guix store)
#:use-module (guix monads)
#:use-module (guix derivations)
#:use-module (guix packages)
#:use-module (gnu packages)
#:use-module (gnu packages bootstrap)
#:use-module ((gnu packages base) #:select (coreutils))
#: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 monads) module.
(define %store
(open-connection-for-tests))
;; Globally disable grafts because they can trigger early builds.
(%graft? #f)
(define %monads
(list %identity-monad %store-monad %state-monad))
(define %monad-run
(list identity
(cut run-with-store %store <>)
(cut run-with-state <> '())))
(define-syntax-rule (values->list exp)
(call-with-values (lambda () exp)
list))
(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))
(g (apply lift1 1+ (list monad))))
(with-monad monad
(let ((number (random 777)))
(= (run (>>= (return number) f))
(run (>>= (return number) g))
(1+ number))))))
%monads
%monad-run))
(test-assert ">>= with more than two arguments"
(every (lambda (monad run)
(let ((1+ (lift1 1+ monad))
(2* (lift1 (cut * 2 <>) monad)))
(with-monad monad
(let ((number (random 777)))
(= (run (>>= (return number)
1+ 1+ 1+
2* 2* 2*))
(* 8 (+ number 3)))))))
%monads
%monad-run))
(test-assert "mbegin"
(every (lambda (monad run)
(with-monad monad
(let* ((been-there? #f)
(number (mbegin monad
(return 1)
(begin
(set! been-there? #t)
(return 2))
(return 3))))
(and (= (run number) 3)
been-there?))))
%monads
%monad-run))
(test-assert "mparameterize"
(let ((parameter (make-parameter 'outside)))
(every (lambda (monad run)
(equal?
(run (mlet monad ((outer (return (parameter)))
(inner
(mparameterize monad ((parameter 'inside))
(return (parameter)))))
(return (list outer inner (parameter)))))
'(outside inside outside)))
%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 "package-file, default system"
;; The default system should be the one at '>>=' time, not the one at
;; invocation time. See <http://bugs.gnu.org/18002>.
(run-with-store %store
(mlet* %store-monad
((system -> (%current-system))
(file (parameterize ((%current-system "foobar64-linux"))
(package-file coreutils "bin/ls")))
(cu (package->derivation coreutils)))
(return (string=? file
(string-append (derivation->output-path cu)
"/bin/ls"))))
#:guile-for-build (package-derivation %store %bootstrap-guile)))
(test-assert "package-file + package->cross-derivation"
(run-with-store %store
(mlet* %store-monad ((target -> "mips64el-linux-gnu")
(file (package-file coreutils "bin/ls"
#:target target))
(xcu (package->cross-derivation coreutils target)))
(let ((output (derivation->output-path xcu)))
(return (string=? file (string-append output "/bin/ls")))))
#:guile-for-build (package-derivation %store %bootstrap-guile)))
(test-assert "interned-file"
(run-with-store %store
(mlet* %store-monad ((file -> (search-path %load-path "guix.scm"))
(a (interned-file file))
(b (interned-file file "b")))
(return (equal? (call-with-input-file file get-string-all)
(call-with-input-file a get-string-all)
(call-with-input-file b get-string-all))))
#: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) (iota 10)))
(map 1+ (iota 10)))))
%monads
%monad-run))
(test-assert "sequence"
(every (lambda (monad run)
(let* ((input (iota 100))
(order '()))
(define (frob i)
(mlet monad ((foo (return 'foo)))
;; The side effect here is used to keep track of the order in
;; which monadic values are bound. Perform the side effect
;; within a '>>=' so that it is performed when the return
;; value is actually bound.
(set! order (cons i order))
(return i)))
(and (equal? input
(run (sequence monad (map frob 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
(anym monad
(lift1 (lambda (x)
(and (odd? x) 'odd!))
monad)
(append (make-list 1000 0)
(list 1 2)))))
'odd!))
%monads
%monad-run))
(test-equal "set-current-state"
(list '(a a d) 'd)
(values->list
(run-with-state
(mlet* %state-monad ((init (current-state))
(init2 (set-current-state 'b)))
(mbegin %state-monad
(set-current-state 'c)
(set-current-state 'd)
(mlet %state-monad ((last (current-state)))
(return (list init init2 last)))))
'a)))
(test-equal "state-push etc."
(list '((z . 2) (p . (1)) (a . (1))) '(2 1))
(values->list
(run-with-state
(mbegin %state-monad
(state-push 1) ;(1)
(state-push 2) ;(2 1)
(mlet* %state-monad ((z (state-pop)) ;(1)
(p (current-state))
(a (state-push z))) ;(2 1)
(return `((z . ,z) (p . ,p) (a . ,a)))))
'())))
(test-end "monads")
