ListBeginsWithList

Type

operator

Summary

Determines whether Source begins with Prefix

Syntax

<Source> begins with <Prefix>

Description

Source begins with Prefix if and only if the elements of Prefix occur as an initial subsequence of the elements of Source.

note

Since the empty list is an initial subsequence of every list, every list begins with the empty list.

Parameters

Name	Type	Description
Prefix		An expression which evaluates to a list.
Source		An expression which evaluates to a list.

Examples

variable tVar as List
put [1, 2, 3, 4, 5] into tVar

variable tBegins as Boolean
// put tList begins with tList[1] into tBegins -- error: tList[1] is not a list 

put tList begins with [1, 2] into tBegins -- tBegins is true