Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot
 
PerlMonks  

Parameter Pattern Matching in Perl

by withering (Scribe)
on Feb 10, 2014 at 13:03 UTC ( #1074239=perlmeditation: print w/ replies, xml ) Need Help??

Hello fellow monks.

A few days ago I was working on type inference in both simply-typed lambda calculus and Hindley-Milner System. While I was trying to use hashtables to implement branches for getting rid of annoying 'if's, I realized that there's no quick ways to emulate pattern matching in ML or Haskell -- It is a fact that we could not easily do that due to the dynamic nature of Perl's type system. However, I managed to emulate some of the features I used in Erlang, ML, or perhaps Haskell and made a small CPAN module HOI::Match (where HOI means Higher-Order Imperative):

HOI::Match

With the module, I am able to write such a sum function:

sub sum { HOI::Match::pmatch( "h :: r" => sub { my %args = @_; $args{h} + sum($args{r}) }, "nil" => sub { 0 } )->(@_) }

(Note that the arguments in @_ may be FETCH several times so it is dangerous to rely on side effects of FETCH on arguments.)

Any suggestion or criticism is welcomed. I am looking forward for your replies.

Comment on Parameter Pattern Matching in Perl
Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: perlmeditation [id://1074239]
Approved by Athanasius
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others surveying the Monastery: (9)
As of 2015-07-29 23:32 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (269 votes), past polls