Here's the example I usually give in talks etc.. Say you have an HTML editor that has bold, underline and italics. Instead of writing three functions, have the compiler write them for you: 

sub mk_tagger {
    my($tag) = @_;
    return sub { my($txt) = @_; "<$tag>$txt</$tag>" };
}
my ($bold, $underline, $italic) = map { mk_tagger($_) } qw( b u i );

print $bold->("what a " . $underline->("nice") . $italic->(" day"));

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Here's the equivalent Perl 6: 

sub mk_tagger ($tag) {
    -> { "<$tag>$^txt</$tag>" }
}

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The idea is that the mk_taggger function is intentionally designed not to be used directly but to generate tagging functions.

Update: In Haskell and other languages that had autocurrying, you'd not need this explicit distinction. 

tagStr :: String -> String -> String
tagStr tag text = "<" ++ tag ++ ">" ++ text ++ "</" ++ tag ++ ">"

-- now I can use it either way.
tagStr "b" "a bold moose"
underline = tagStr "u"
underline "an underlined moose"

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In reply to Re: Currying--useful examples? by gaal
in thread Currying--useful examples? by macrobat

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