[eru]

Type classes are built into the language. So they are not really `design patterns' by the original definition of the word.

[comex]

To be fair, most of these classes come with "laws" instances are supposed to follow, which are not encoded in the language...

[Fixnum]

On the other hand, the burden of proof is on the library writer who creates the typeclass instance, not on the end user - possible largely thanks to purity - whereas programmers may expect to re-implement various patterns by hand.

[eru]

Good point!

[Dewie]

That was partly my point, at least for functional languages that can express these concepts, like certain statically typed ones.