▼scramble:   Assorted Utility Libraries
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K
K0
call
8.16.0.4
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6 Functions🔗ℹ

 (require scramble/function) package: scramble-lib

procedure

(K v ...) → procedure?

  v : any/c
Returns a constant function that produces (values v ...) when applied.

The resulting constant function’s arity is (arity-at-least 0); that is, it accepts (and discards) any number of positional arguments, but it does not accept keyword arguments. See const for a single-valued version whose result accepts keyword arguments.

Examples:
> (define always-zero (K 0))
> (map always-zero '(1 2 3))

'(0 0 0)

> (define two-falses (K #f #f))
> (define-values (head tail)
    (with-handlers ([exn? two-falses])
      (values (car '()) (cdr '()))))

procedure

(K0 v ...) → procedure?

  v : any/c
Like K, but the resulting constant function’s arity is 0 (with no keywords).

procedure

(call f v ...) → any

  f : procedure?
  v : any/c
Calls f on the arguments v ...; equivalent to (f v ...). Primarily useful as an argument to higher-order functions.

Examples:
> (define the-callbacks
    (list (lambda () (printf "here I am\n"))
          (lambda () (printf "me too!\n"))))
> (map call the-callbacks)

here I am

me too!

'(#<void> #<void>)

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