List type

[yb66]

Hi,

Really like the look of this library, though I'm struggling to use or define a/the list type. I tried defining my own and I've tried using the one in lib/algebrick/types.rb - I'm not even sure I should be calling that directly. I'm at a bit of a loss. Is there an example for this somewhere, or do you know of a library using it? (real world examples are always best:)

Any help or insight would be much appreciated.

Regards,
iain

[yb66]

Perhaps an example of what I'm trying to achieve would be helpful. I want to define a Rose Tree. In Haskell it might be data Rose a = Node a [Rose a]

My attempt with Algebrick:

RoseTree = Algebrick.type do |rosetree|
  variants Empty = atom,
               Node  = type { fields Integer, Algebrick::List[rosetree] }
end

The error is:

TypeError: fields or variants have to be set
from /Users/iainb/Projects/algebrick/lib/algebrick/product_variant.rb:161:in `kind'

I'm probably missing something obvious.

Regards,
iain