tomo-List.where.3

(37 lines)
   1 '\" t
   2 .\" Copyright (c) 2026 Bruce Hill
   3 .\" All rights reserved.
   4 .\"
   5 .TH List.where 3 2026-03-08 "Tomo man-pages"
   6 .SH NAME
   7 List.where \- find an index where a predicate matches
   8 .SH LIBRARY
   9 Tomo Standard Library
  10 .SH SYNOPSIS
  11 .nf
  12 .BI List.where\ :\ func(list:\ [T],\ predicate:\ func(item:&T\ ->\ Bool)\ ->\ Int)
  13 .fi
  14 .SH DESCRIPTION
  15 Find the index of the first item that matches a predicate function (if any).
  16 
  17 
  18 .SH ARGUMENTS
  19 
  20 .TS
  21 allbox;
  22 lb lb lbx
  23 l l l.
  24 Name	Type	Description
  25 list	[T]	The list to search through. 
  26 predicate	func(item:&T -> Bool)	A function that returns \fByes\fR if the item's index should be returned or \fBno\fR if it should not. 
  27 .TE
  28 .SH RETURN
  29 Returns the index of the first item where the predicate is true or `none` if no item matches.
  30 
  31 .SH EXAMPLES
  32 .EX
  33 assert ["BC", "ABC", "CD"].where(func(t:&Text) t.starts_with("A")) == 2
  34 assert ["BC", "ABC", "CD"].where(func(t:&Text) t.starts_with("X")) == none
  35 .EE
  36 .SH SEE ALSO
  37 .BR Tomo-List (3)