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Programming-Idioms

History of Idiom 12 > diff from v125 to v126

Edit summary for version 126 by Anon:
[Scheme] Fix error

Version 125

2020-12-16, 22:09:38

Version 126

2020-12-16, 22:45:30

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
(if (null? list) #f
  (begin
    (if (equal? (car list) x) #t
    (contains? (cdr list) x)))))
Code
(define (contains? list x)
  (if (null? list) #f
    (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