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Programming-Idioms

History of Idiom 12 > diff from v124 to v125

Edit summary for version 125 by Anon:
[Scheme] Previous doesn't work in chez scheme

Version 124

2020-12-08, 21:41:56

Version 125

2020-12-16, 22:09:38

Idiom #12 Check if list contains a value

Check if list contains a value x.
list is an iterable finite container.

Idiom #12 Check if list contains a value

Check if list contains a value x.
list is an iterable finite container.

Variables
list,x
Variables
list,x
Extra Keywords
array vector member membership
Extra Keywords
array vector member membership
Code
(define (contains list x)
        (if (null? list) #f)
        (if (equal? (car list) x) #t)
        (else (contains (cdr list) x))))
Code
(if (null? list) #f
  (begin
    (if (equal? (car list) x) #t
    (contains? (cdr list) x)))))
Comments bubble
This is a custom implementation, use it if no built-in predicate is available in your Scheme environment.
Comments bubble
This is a custom implementation, use it if no built-in predicate is available in your Scheme environment.
Demo URL
https://repl.it/@ProgIdioms/SteelbluePhonyTerrapin-1
Demo URL
https://repl.it/@ProgIdioms/SteelbluePhonyTerrapin-1