auto-detecting Perl source files

gistfile1.md

Language dialect:

• --perl as a catch-all
• --perl5 and --perl6 for files that can positively identified as one or the other

Criteria for the latter:

• file extension: .p5, .pl5, .pm5 vs .p6, .pl6, .pm6
• shebang
• use v* in first (non-shebang or non-comment?) line for files with generic extension

Edge cases:

1. no shebang or use at start of file
2. shebang disagrees with use
3. freely intermixed p5/p6 blocks with lexical use (not possible right now, but one can dream...)

Pragmatic resolution strategy:

1. only detect as --perl
2. detect as both --perl5 and --perl6
3. only detect as --perl

Alternative resolution strategy:

• look for heuristics that discern p5 and p6 code

Personal preference is the pragmatic solution, as the latter is brittle and slow