This looks like syntax error with map in list context. The documentation for map says "{ starts both hash references and blocks, so map { ... could be either the start of map BLOCK LIST or map EXPR, LIST." This syntax works as well as the one you discovered: 

my %h = map { +"$_" => "$_" } @arr ;

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In reply to Re: strange map behavior by kyle
in thread strange map behavior by jeanluca

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