The +* is a "key extractor" closure. This closure corresponds to the before map of the ST. Of course, in the specific case of +*, it's trivial to instead just specify a "comparator" closure using <=>, but what if one instead writes: 

say sort +*.value, 1=>4,  11=>5,  2=>99,  22=>22,  3=>339
# prints           1=>4   11=>5   22=>22  2=>99    3=>339

say sort ~*.value, 1=>4,   11=>5,  2=>99,  22=>22,  3=>339
# prints           22=>22  3=>339  1=>4    11=>5    2=>99

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(And of course the results of the closure call on a given item is memoized.)

»ö« . o O ( "the celebrity tell-all of the Perl-6 cult?" )

In reply to Re^4: sort +*, @array by raiph
in thread sort +*, @array by raiph

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