Monads/List monad: Difference between revisions

=== Vanilla Racket ===

;; => '((3 4 5) (5 12 13) (6 8 10) (8 15 17) (9 12 15) (12 16 20))</lang>

=== With functional package ===

The [https://docs.racket-lang.org/functional/interfaces.html functional] package has already implemented the list monad.

<lang racket>#lang racket

(require data/monad

data/applicative)

(define (pythagorean-triples n)

(sequence->list

(do [x <- (range 1 n)]

[y <- (range (add1 x) n)]

[z <- (range (add1 y) n)]

(if (= (+ (* x x) (* y y)) (* z z))

(pure (list x y z))

'()))))

(pythagorean-triples 25)