For the first question, read further. "The range operator (in list context) makes use of the magical auto-increment algorithm if the operands are strings."

For the second question, you got bitten by the side-effect of an optimisation. Constant ranges are expanded into a list at compile-time. You modified this list, affecting future use of it. Workaround: 

for ('a'..'f') {
   my $letter = $_;  # Make modifiable copy
   ...
}

[download]

Update: Misunderstood the first question

In reply to Re: Two Range Operator Anomalies by ikegami
in thread Two Range Operator Anomalies by liverpole

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