[Haskell-cafe] Strong duck typing / structural subtyping / type class aliases / ??? in Haskell

[wren ng thornton]

Peter Verswyvelen wrote:
> After having read an email in the cafe about the Noop language & Self
> language, I realized that what I really would like to have is "strong duck
> typing" on records (or is it called structural subtyping? or
> prototype-based-objects? or something like that)

The common name for (one form of) what you're seeking is "row polymorphism":

   http://www.cs.cmu.edu/~neelk/rows.pdf

This is implemented in OCaml but, like most OO features in functional 
languages, it is often ignored or forgotten about. As others've 
mentioned, there are some cases where row polymorphism is really nice, 
but it's not always semantically coherent.

-- 
Live well,
~wren