[Redirecting to haskell-cafe] Ben Franksen wrote:
TREX seems to be generally agreed to be too complicated to implement and explain.
What evidence do you have for this? Speaking as somebody who implemented Trex for Hugs (and who also witnessed Ben Gaster build an independent implementation), I'd have to disagree about the first part of this. As I recall, the implementation was reasonably straightforward, and wasn't any more complicated than other common type system extensions that I've worked on. I'm also not sure why you think it is complicated to explain, but I suppose that's even more subjective. One of the most difficult things about the Trex implementation was finding a syntax that meshed nicely with the rest of the Haskell syntax. This is likely to be a problem for any record system extension of Haskell---unless you're prepared to accept a more unconventional syntax---because many of the symbols that you might want to use ({, }, ., |, \, for example) have already been adopted for other purposes. Ah, syntax! All the best, Mark