From: Eivind Eklund <eeklund@...>
Date: 2008-02-01T06:47:48+09:00
Subject: Re: Gedankenexperiment on method duck type safety

On Jan 31, 2008 8:25 PM, Tim Connor <timocratic@gmail.com> wrote:
> And I know this doesn't fit with he already complex enough method
> declarations in ruby.  It's just faux ruby style, because that is my
> favorite dynamic language. So, without further prevarication, here is
> the aforementioned abomination, for either discussion sake, or
> pointing and laughing, whichever floats your boat:
>
> def foo(bar.is_? Array, !bar.is_empty?, baz.responds_to :webbed_feet)

See code implementing something similar at
http://people.freebsd.org/~eivind/ruby/types/

typesig Type::And(Array, Type::RespondFalse(:is_empty?)),
Type::RespondTo(:webbed_feet)
def foo(bar, baz)
   ...
end

You'd have to implement Type::RespondFalse - should be trivial.

Eivind.