foldl is a lot like reduce in the
List::Util module, which I believe will be a
builtin in Perl 6.
foldl is also a lot like foldl
in the Language::Functional module. :-)
Also, I know you're trying to keep it reasonably short, but I think it would be really cool to show an example of constructing recursive polymorphic types, and the fact that you can have different data constructors with completely different type arguments. In other words, the fact that in Haskell you can implement large parts of your program logic just by the way you design your types.
I'm getting there... I'm planning to talk about Haskell's
typing system in more detail in a later installment.
Found a typo in this node? /msg me
% man 3 strfry