+++ /dev/null
-'\"
-'\" Copyright (c) 2012 Trevor Davel
-'\"
-'\" See the file "license.terms" for information on usage and redistribution
-'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
-'\"
-.TH lmap n "" Tcl "Tcl Built-In Commands"
-.so man.macros
-.BS
-'\" Note: do not modify the .SH NAME line immediately below!
-.SH NAME
-lmap \- Iterate over all elements in one or more lists and collect results
-.SH SYNOPSIS
-\fBlmap \fIvarname list body\fR
-.br
-\fBlmap \fIvarlist1 list1\fR ?\fIvarlist2 list2 ...\fR? \fIbody\fR
-.BE
-.SH DESCRIPTION
-.PP
-The \fBlmap\fR command implements a loop where the loop variable(s) take on
-values from one or more lists, and the loop returns a list of results
-collected from each iteration.
-.PP
-In the simplest case there is one loop variable, \fIvarname\fR, and one list,
-\fIlist\fR, that is a list of values to assign to \fIvarname\fR. The
-\fIbody\fR argument is a Tcl script. For each element of \fIlist\fR (in order
-from first to last), \fBlmap\fR assigns the contents of the element to
-\fIvarname\fR as if the \fBlindex\fR command had been used to extract the
-element, then calls the Tcl interpreter to execute \fIbody\fR. If execution of
-the body completes normally then the result of the body is appended to an
-accumulator list. \fBlmap\fR returns the accumulator list.
-.PP
-In the general case there can be more than one value list (e.g., \fIlist1\fR
-and \fIlist2\fR), and each value list can be associated with a list of loop
-variables (e.g., \fIvarlist1\fR and \fIvarlist2\fR). During each iteration of
-the loop the variables of each \fIvarlist\fR are assigned consecutive values
-from the corresponding \fIlist\fR. Values in each \fIlist\fR are used in order
-from first to last, and each value is used exactly once. The total number of
-loop iterations is large enough to use up all the values from all the value
-lists. If a value list does not contain enough elements for each of its loop
-variables in each iteration, empty values are used for the missing elements.
-.PP
-The \fBbreak\fR and \fBcontinue\fR statements may be invoked inside
-\fIbody\fR, with the same effect as in the \fBfor\fR and \fBforeach\fR
-commands. In these cases the body does not complete normally and the result is
-not appended to the accumulator list.
-.SH EXAMPLES
-.PP
-Zip lists together:
-.PP
-.CS
-set list1 {a b c d}
-set list2 {1 2 3 4}
-set zipped [\fBlmap\fR a $list1 b $list2 {list $a $b}]
-# The value of zipped is "{a 1} {b 2} {c 3} {d 4}"
-.CE
-.PP
-Filter a list to remove odd values:
-.PP
-.CS
-set values {1 2 3 4 5 6 7 8}
-proc isEven {n} {expr {($n % 2) == 0}}
-set goodOnes [\fBlmap\fR x $values {expr {
- [isEven $x] ? $x : [continue]
-}}]
-# The value of goodOnes is "2 4 6 8"
-.CE
-.PP
-Take a prefix from a list based on the contents of the list:
-.PP
-.CS
-set values {8 7 6 5 4 3 2 1}
-proc isGood {counter} {expr {$n > 3}}
-set prefix [\fBlmap\fR x $values {expr {
- [isGood $x] ? $x : [break]
-}}]
-# The value of prefix is "8 7 6 5 4"
-.CE
-.SH "SEE ALSO"
-break(n), continue(n), for(n), foreach(n), while(n)
-.SH KEYWORDS
-foreach, iteration, list, loop, map
-'\" Local Variables:
-'\" mode: nroff
-'\" End:
OSDN Git Service
