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(set! %load-path (cons "." %load-path))
(use-modules (monad maybe)
(monad either)
(monad state))
(define (test name expr expectation)
(let ((res (eval expr (interaction-environment))))
(if (equal? res expectation)
(format #t "[~s] passed\n" name)
(format #t "[~s] ERROR: expected: ~s, but got: ~s\n" name expectation res))))
(define (f x)
(if (> x 0)
(Just x)
(Nothing)))
(begin
(test "maybe 1"
'(with-monad maybe-monad
(a <- (Just 5))
(b <- (f 2))
(c <- (Just 10))
(return (+ a b c)))
(Just 17))
(test "maybe 2"
'(with-monad maybe-monad
(a <- (Just 5))
(b <- (f 0))
(c <- (Just 10))
(return (+ a b c)))
(Nothing))
(test "state 1"
'(run-state 0 (with-monad state-monad
(put 10)
(put 9)
(modify (lambda (x) (+ 2 x)))
(modify (lambda (x) (+ 2 x)))
(get)))
13)
(test "state 2"
'(run-state 10 (with-monad state-monad
(get)))
10)
(test "either 1"
'(with-monad either-monad
(a <- (Right 5))
(b <- (Right 0))
(c <- (Right 10))
(return (+ a b c)))
(Right 15))
(test "either 2"
'(with-monad either-monad
(a <- (Right 5))
(b <- (Left "an error"))
(c <- (Right 10))
(return (+ a b c)))
(Left "an error")))
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