From: ptkwt@... (Phil Tomson)
Date: 2003-11-21T06:52:16+09:00
Subject: Re: Partial Euphoric Type Checking

In article <E1AMvnC-0002fH-T7@odie.runbox.com>,
T. Onoma <transami@runbox.com> wrote:
>Greetings all Type Checkers!
>
>I have implemented a version of euphoria's type system in Ruby.
>
>  # the good stuff
>
>  module Kernel
>    def typechecking(x=nil)
>      return $_tc if x == nil
>      $_tc = x ? true : false
>    end
>  end
>
>  class Module
>    def type(tname, &check)
>      define_method(tname) do |*v|
>        if $_tc
>          unless v.all? { |y| check.call(y) }
>            raise TypeError
>          end
>        end
>        return *v
>      end
>    end
>  end
>
>  # demonstrate how it feels
>
>  class TypeTest
>    type :big4 do |x|
>      x > 4
>    end
>    def ameth(x)
>      # -- type checking --
>      big4 x  
>      # -- rest of code --
>      puts x
>    end
>  end
>
>  typechecking true  # turn type checking on
>  t = TypeTest.new
>  t.ameth(5)  # => 5
>  t.ameth(2)  # => TypeError
>
>Now if you can just get matz to add a little sytax sugar for type and
>inline parameter methods:

Why does Matz need to add any sugar?  You show how it can be done above.  
Sure, it would make what you're trying to do look a little nicer, but why 
don't you just release your code above as a module on the RAA and document 
it nicely and then people can use it if they wish (and not use it if they wish).

>
>  class TypeTest
>    type big4(x)
>      x > 4
>    end
>    def ameth(big4 x)
>      puts x
>    end
>  end
>
>would that quell the need?

It's got it's uses but I wouldn't hold my breath for any sugar ;-)

Phil