Higher-order function: Difference between revisions

Revision as of 19:50, 8 September 2022

Revision as of 12:53, 30 March 2023

Line 763:

<syntaxhighlight lang="scheme">

(define (addtwice x yf) (+ x y))

(definelambda (x) (f (f x))))

(lambda (y) (+ x y)))

(display ((f 3) 7))

(display (add 3 7))

</syntaxhighlight>

In this Scheme example, the higher-order function {{code|(f x)}} is used to implement [[currying]]. It takes a single argument and returns a function. The evaluation of the expression {{code|((f 3) 7)}} first returns a function after evaluating {{code|(f 3)}}. The returned function is {{code|(lambda (y) (+ 3 y))}}. Then, it evaluates the returned function with 7 as the argument, returning 10. This is equivalent to the expression {{code|(add 3 7)}}, since {{code|(f x)}} is equivalent to the curried form of {{code|(add x y)}}.

====Swift====