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Re^2: Things I Don't Use in Perl

by fizbin (Chaplain)
on Aug 29, 2005 at 00:41 UTC ( #487310=note: print w/replies, xml ) Need Help??

in reply to Re: Things I Don't Use in Perl
in thread Things I Don't Use in Perl

Maybe it's just that I was a math major, or got too close to those whacky Haskell nuts, but map has always seemed a very natural metaphor for me. (It's the natural extension of a function on a space A to the space An)

However, this (map is natural instead of foreach) is only true when the expression inside the map isn't itself accumulating side-effects; e.g. the following useage of map doesn't seem natural:

my $i=0; map {$keywordhash{$_}=(++$i);} @keywords;
However, this useage seems quite natural:
%keywordhash = map {$_ => 1} @keywords;
I guess you could also distinguish these two cases by noting that one calls map in void context whereas the other does not; while that's true, I think I'd still prefer
do {$keywordhash{$_}=(++$i);} for @keywords;
%keywordhash = map { $_ => ++$i } @keywords;
Even though I like map, because I'm not completely comfortable with the idea of depending on a certain execution order for map, even though I know it has one. When I'm thinking in a linear, this-gets-executed-then-this mode, map rarely makes sense. map does however make sense as a higher-order function, and when I'm thinking like that it's quite natural.

(Of course, all style niceties get completely discarded inside JAPHs)

@/=map{[/./g]}qw/.h_nJ Xapou cets krht ele_ r_ra/; map{y/X_/\n /;print}map{pop@$_}@/for@/

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