The comma in ,=> is a NOP. 

  DB<8> x ["a",=>"b"]
0  ARRAY(0x54e32f0)
   0  'a'
   1  'b'
  DB<9> x ["a",,"b"]
0  ARRAY(0x54e2cd8)
   0  'a'
   1  'b'

[download]

Like choroba already explained it's a syntactic trick to avoid lc to be stringified by =>

edit

so whats happening is a construction of hash pairs, where the keys are normalized to lowercase. The fat-comma is meant to clarify this pair nature.

  DB<12> x map {lc,$_} "A".."C"
0  'a'
1  'A'
2  'b'
3  'B'
4  'c'
5  'C'

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

In reply to Re: Strange grep construct by LanX
in thread Strange grep construct by mzvk

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