Exegesis 6 (Perl 6 Subroutines) Released

chromatic writes "Perl.com has just published Damian Conway's Exegesis 6 which gives practical examples demonstrating how to use the new subroutine and method semantics in Perl 6. This is the companion to Larry Wall's Apocalypse 6 which discussed the changes planned for subroutines in Perl 6."

Comments

Any Sufficiently Advanced Language...

[Vagary]

A disclaimer: I used to program Perl for a living, but we had a falling out some years ago (around 5.0?). So if you don't think there's any merit to what I'm saying, then feel free to consider this a troll:

Shortly after I started reading Exegesis 6 I was somewhat frightened by how complex Perl had become since I stopped keeping track of updates. Of course scripting languages have always been known for borrowing the best from other programming languages, so I kept reading in the hopes that I'd recognise something. I saw some features like the is constant declaration and started worrying that maybe they'd decided to borrow some features from the very popular but insanely evil Visual Basic. But then I saw this:

type Selector ::= Code | Class | Rule | Hash;

and realised that, just as Python is (alleged to be?) adding Lisp-like features, Perl is adding ML-like features! That line above is (minus the '::' and ';') straight out of a Haskell program. Then I started to notice more Haskell-like syntax:

• Anonymous function declaration syntax: -> $animal { $animal.size < $breadbox } would be (\animal -> animal.size < breadbox) in Haskell
• Multisubs are like pattern matching: multi sub feed(Cat $c) {...} multi sub feed(Lion $l) {...} would be
  feed (Cat c) = ...
  feed (Lion l) = ...
• New infix operator definitions: infix:~|_|~ would be the function named (~|_|~)
• Junctions are like list comprehensions: all(newvals) would be [x | x <- newvals] (it almost seems like junctions are lazy from the way Damian talks about them?!)

And I'm sure a more thorough reading would turn up even more. (For example, the smart-match operator reminds me of the type inferences done in a Hindley-Milner type system.) So it appears that any sufficiently advanced language contains an implementation of a purely functional language, not specifically Scheme. :) Has Damian (who certainly has Haskell exposure) or Larry ever mentioned any of these influences?