ltake ( list n -- result )
Lazy lists » Manipulating lazy lists

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Vocabulary
lists.lazy

Inputs

list	a cons object
n	a non negative integer

Outputs

result

resulting cons object

Word description
Outputs a lazy list containing the first n items in the list. This is done a lazy manner. No evaluation of the list elements occurs initially but a lazy-take object is returned which conforms to the list protocol. Calling car, cdr or nil? on this will evaluate elements as required.

Examples

USING: kernel lists lists.lazy prettyprint ; 1 lfrom 5 ltake list>array .
{ 1 2 3 4 5 }

See also
leach, foldl, lmap-lazy, lfilter, lappend-lazy, lfrom, lfrom-by, lconcat, lcartesian-product, lcartesian-product*, lcartesian-map, lcartesian-map*, lmerge, lwhile, luntil

Definition

USING: kernel lists math ;

IN: lists.lazy

: ltake ( list n -- result )
    dup zero? [ 2drop nil ] [ <lazy-take> ] if ;