Re: [Haskell-cafe] Design Patterns by Gamma or equivalent

Am Dienstag, 17. März 2009 05:09 schrieb wren ng thornton:

ajb@spamcop.net wrote:

...

Or to put it another way, category theory is the pattern language of mathematics.

Indeed. Though, IMO, there's a distinction between fairly banal things (e.g. monoids),

Monoids aren’t a concept of category theory. There are a generalization of groups. So they more belong to group theory. By the way, the documentation of Control.Category says that a category is a monoid (as far as I remember). This is wrong. Category laws correspond to monoid laws but monoid composition is total while category composition has the restriction that the domain of the first argument must match the codomain of the second. Best wishes, Wolfgang