head
| Definition: | sequence res = head(sequence src, integer size=1) |
| Description: |
Return the first
size elements of
src.
src: the sequence from which elements will be obtained. size: number of elements required. If omitted, returns src[1..1]. Returns a sequence containing the first size elements of src, unless it is
shorter than size, in which case src is returned unaltered.
|
| pwa/p2js: | Supported. |
| Comments: | NB when size is omitted this returns src[1..1] rather than src[1]. |
| Example: |
s2 = head("John Doe", 4) -- s2 is John
s2 = head("John Doe", 50) -- s2 is John Doe
s2 = head({1, 5.4, "John", 30}, 3) -- s2 is {1, 5.4, "John"}
s2 = head({1, 2, 3, 4}) -- s2 is {1}
|
| Implementation: | See builtins\pseqc.e (an autoinclude) for details of the actual implementation. |