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-rw-r--r--doc/apply.n46
1 files changed, 26 insertions, 20 deletions
diff --git a/doc/apply.n b/doc/apply.n
index 8a38aac..9d373e1 100644
--- a/doc/apply.n
+++ b/doc/apply.n
@@ -48,30 +48,32 @@ The semantics of \fBapply\fR can also be described by:
.PP
.CS
proc apply {fun args} {
- set len [llength $fun]
- if {($len < 2) || ($len > 3)} {
- error "can't interpret \e"$fun\e" as anonymous function"
- }
- lassign $fun argList body ns
- set name ::$ns::[getGloballyUniqueName]
- set body0 {
- rename [lindex [info level 0] 0] {}
- }
- proc $name $argList ${body0}$body
- set code [catch {uplevel 1 $name $args} res opt]
- return -options $opt $res
+ set len [llength $fun]
+ if {($len < 2) || ($len > 3)} {
+ error "can't interpret \e"$fun\e" as anonymous function"
+ }
+ lassign $fun argList body ns
+ set name ::$ns::[getGloballyUniqueName]
+ set body0 {
+ rename [lindex [info level 0] 0] {}
+ }
+ proc $name $argList ${body0}$body
+ set code [catch {uplevel 1 $name $args} res opt]
+ return -options $opt $res
}
.CE
.SH EXAMPLES
+.PP
This shows how to make a simple general command that applies a transformation
to each element of a list.
+.PP
.CS
proc map {lambda list} {
- set result {}
- foreach item $list {
- lappend result [\fBapply\fR $lambda $item]
- }
- return $result
+ set result {}
+ foreach item $list {
+ lappend result [\fBapply\fR $lambda $item]
+ }
+ return $result
}
map {x {return [string length $x]:$x}} {a bb ccc dddd}
\fI\(-> 1:a 2:bb 3:ccc 4:dddd\fR
@@ -81,11 +83,12 @@ map {x {expr {$x**2 + 3*$x - 2}}} {-4 -3 -2 -1 0 1 2 3 4}
.PP
The \fBapply\fR command is also useful for defining callbacks for use in the
\fBtrace\fR command:
+.PP
.CS
set vbl "123abc"
trace add variable vbl write {\fBapply\fR {{v1 v2 op} {
- upvar 1 $v1 v
- puts "updated variable to \e"$v\e""
+ upvar 1 $v1 v
+ puts "updated variable to \e"$v\e""
}}}
set vbl 123
set vbl abc
@@ -93,4 +96,7 @@ set vbl abc
.SH "SEE ALSO"
proc(n), uplevel(n)
.SH KEYWORDS
-argument, procedure, anonymous function
+anonymous function, argument, lambda, procedure,
+'\" Local Variables:
+'\" mode: nroff
+'\" End: