165 lines
5.3 KiB
Racket
165 lines
5.3 KiB
Racket
;;; typed-compose.rkt
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;;;
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;;; Copyright 2020 Sergiu Ivanov <sivanov@colimite.fr>
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;;;
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;;; This program is free software: you can redistribute it and/or
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;;; modify it under the terms of the GNU General Public License as
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;;; published by the Free Software Foundation, either version 3 of the
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;;; License, or (at your option) any later version.
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;;;
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;;; This program is distributed in the hope that it will be useful,
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;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;;; 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 this program. If not, see
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;;; <https://www.gnu.org/licenses/>.
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#lang typed/racket
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(require (for-syntax syntax/parse))
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(provide compose-n
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compose-3 compose-4 compose-5 compose-6 compose-7 compose-8 compose-9
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multi-compose multi-chain)
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(module+ test
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(require typed/rackunit))
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(: compose-n (All (a) (-> (-> a a) * (-> a a))))
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(define (compose-n . funcs)
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(λ (x)
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(for/foldr ([x x]) ([f funcs])
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(f x))))
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(module+ test
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(test-case "compose-n"
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(check-equal? ((compose-n add1 add1 add1) 3) 6)))
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(: compose-3 (All (a b c d)
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(-> (-> c d)
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(-> b c)
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(-> a b)
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(-> a d))))
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(define (compose-3 f1 f2 f3)
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(λ (x) (f1 (f2 (f3 x)))))
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(: compose-4 (All (a b c d e)
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(-> (-> d e)
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(-> c d)
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(-> b c)
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(-> a b)
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(-> a e))))
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(define (compose-4 f1 f2 f3 f4)
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(λ (x) (f1 (f2 (f3 (f4 x))))))
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(: compose-5 (All (a b c d e f)
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(-> (-> e f)
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(-> d e)
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(-> c d)
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(-> b c)
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(-> a b)
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(-> a f))))
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(define (compose-5 f1 f2 f3 f4 f5)
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(λ (x) (f1 (f2 (f3 (f4 (f5 x)))))))
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(: compose-6 (All (a b c d e f g)
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(-> (-> f g)
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(-> e f)
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(-> d e)
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(-> c d)
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(-> b c)
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(-> a b)
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(-> a g))))
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(define (compose-6 f1 f2 f3 f4 f5 f6)
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(λ (x) (f1 (f2 (f3 (f4 (f5 (f6 x))))))))
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(: compose-7 (All (a b c d e f g h)
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(-> (-> g h)
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(-> f g)
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(-> e f)
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(-> d e)
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(-> c d)
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(-> b c)
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(-> a b)
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(-> a h))))
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(define (compose-7 f1 f2 f3 f4 f5 f6 f7)
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(λ (x) (f1 (f2 (f3 (f4 (f5 (f6 (f7 x)))))))))
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(: compose-8 (All (a b c d e f g h i)
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(-> (-> h i)
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(-> g h)
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(-> f g)
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(-> e f)
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(-> d e)
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(-> c d)
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(-> b c)
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(-> a b)
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(-> a i))))
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(define (compose-8 f1 f2 f3 f4 f5 f6 f7 f8)
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(λ (x) (f1 (f2 (f3 (f4 (f5 (f6 (f7 (f8 x))))))))))
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(: compose-9 (All (a b c d e f g h i j)
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(-> (-> i j)
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(-> h i)
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(-> g h)
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(-> f g)
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(-> e f)
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(-> d e)
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(-> c d)
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(-> b c)
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(-> a b)
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(-> a j))))
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(define (compose-9 f1 f2 f3 f4 f5 f6 f7 f8 f9)
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(λ (x) (f1 (f2 (f3 (f4 (f5 (f6 (f7 (f8 (f9 x)))))))))))
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(module+ test
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(test-case "compose-3 to compose-9"
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(define (s->n [s : String]) (cast (string->number s) Number))
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(define (n->s [n : Number]) (number->string n))
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(check-equal? ((compose-3 n->s add1 s->n) "3") "4")
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(check-equal? ((compose-4 n->s add1 add1 s->n) "3") "5")
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(check-equal? ((compose-5 n->s add1 add1 add1 s->n) "3") "6")
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(check-equal? ((compose-6 n->s add1 add1 add1 add1 s->n) "3") "7")
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(check-equal? ((compose-7 n->s add1 add1 add1 add1 add1 s->n) "3") "8")
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(check-equal?
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((compose-8 n->s add1 add1 add1 add1 add1 add1 s->n) "3") "9")
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(check-equal?
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((compose-9 n->s add1 add1 add1 add1 add1 add1 add1 s->n) "3") "10")))
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(define-syntax (multi-compose stx)
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;; Implementation by Sorawee Porncharoenwase.
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(syntax-parse stx
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[(_ f:expr g:expr)
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#'(compose f g)]
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[(_ f:expr funcs:expr ...)
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#'(compose f (multi-compose funcs ...))]))
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(module+ test
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(test-case "multi-compose"
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(check-equal? ((multi-compose add1
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(λ ([x : Number]) (* x 3))
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add1
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(λ ([x : Number]) (+ x 2)))
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3)
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19)))
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(define-syntax (multi-chain stx)
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(syntax-parse stx
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[(_ funcs:expr ...)
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(define rev-funcs (reverse (syntax->list #'(funcs ...))))
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#`(multi-compose #,@rev-funcs)]))
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(module+ test
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(test-case "multi-chain and multi-compose"
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(define f1 (λ ([x : Number]) (displayln "f1") (+ x 1)))
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(define f2 (λ ([x : Number]) (displayln "f2") (+ x 1)))
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(define f3 (λ ([x : Number]) (displayln "f3") (+ x 1)))
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(check-equal?
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(with-output-to-string (λ () (displayln ((multi-chain f1 f2 f3) 3))))
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"f1\nf2\nf3\n6\n")
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(check-equal?
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(with-output-to-string (λ () (displayln ((multi-compose f1 f2 f3) 3))))
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"f3\nf2\nf1\n6\n")))
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