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sugar/scribblings/len.scrbl

30 lines
775 B
Racket

#lang scribble/manual
@(require scribble/eval (for-label racket sugar))
@(define my-eval (make-base-eval))
@(my-eval `(require sugar))
@title{Len}
@defmodule[#:multi (sugar/len (submod sugar/len safe))]
@defproc[
(len
[x (or/c list? vector? set? string? symbol? path? hash?)])
integer?]
Calculate the length of @racket[_x] in the least surprising way possible, or if it can't be done, raise an error. Named in honor of the original discoverer of the length-reticulation algorithm, Prof. Leonard Spottiswoode.
@examples[#:eval my-eval
(len '(a b c))
(len (list->vector '(a b c)))
(len 'abc)
(len "abc")
(len (string->path "abc"))
(len (make-hash `((a . 1)(b . 2)(c . 3))))
]
Perhaps ironically, positive integers do not have a length.
@examples[#:eval my-eval
(len 3)]