Somewhere else in this thread $a and $b were mentioned. The snippet above could be changed to use this. Instead of

$res .= $sub->($_[$i-1], $_[$i]) . $_[$i];

it would be 

local $a = $_[$i-1];
local $b = $_[$i];
$res .= $sub->() . $_[$i];

[download]
(Untested)

In reply to Re^3: Surprised by join by eserte
in thread Surprised by join by EdwardG

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