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Added cond function to Userlib

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Added the cond function to Userlib, also added the associated tests
and documentation.
This commit is contained in:
dariof4 2023-06-13 00:18:11 +02:00
parent fb724ccee4
commit bd23198009
3 changed files with 68 additions and 1 deletions
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30
snippets/userlib-tests.rls
View file

@ -55,6 +55,36 @@
(adder (lambda (x y) (add x y))))
(eq? (reduce adder list) (add 1 2 3)))))
('cond evaluates the first branch that returns true'
(quote
(let ((switch-one false)
(switch-two false)
(switch-three false))
(cond (q
((false (toggle switch-one))
(true (toggle switch-two))
(true (toggle switch-three)))))
(and (not switch-one) switch-two (not switch-three)))))
('cond doesnt do anything if all the branches are false'
(quote
(let ((switch-one false)
(switch-two false)
(switch-three false))
(cond (q
((false (toggle switch-one))
(false (toggle switch-two))
(false (toggle switch-three)))))
(and (not switch-one) (not switch-two) (not switch-three)))))
('cond returns the result of the branch that is evaluated'
(quote
(let ((variable false))
(set (q variable)
(cond (q
((true true)))))
variable)))
('contains? finds elem in list'
(quote
(contains? (1 2 3) 1)))

14
snippets/userlib.rls
View file

@ -84,6 +84,20 @@ this will continue iuntil the list is exhausted.'
(set (q list-iter) (pop remaining)))))
result))
(def cond
'Takes one argument: a list of pairs consisting of a form returning a bool and a form to execute
The function iterates over the list checking if the first form of a pair evaluates to true, in which
case it will execute the second form of the pair, returning its result, and stop the loop.'
(list)
(let ((iter list))
(while (gt? (len iter) 0)
(let ((current (car iter))
(remaining (pop iter)))
(if (eval (car current))
(car (pop ((set (q iter) ())
(eval (cdr current)))))
(set (q iter) (cdr remaining)))))))
(def contains?
'Takes two arguments: a list and an element.
Returns true if the list contains the element.'