On Mon, Aug 14, 2006 at 12:00:25PM -0700, Iavor Diatchki wrote:
As far as I understand, this was done to make it easier to learn Haskell, by turning errors like "Cannot discharge constraint 'Functor X'" into "X =/= List". I am not convinced that this motivation is justified, although I admit that I have very limited experience with teaching functional programming to complete beginners.
I think it is more because if you make too many things overloadable, you get ambiguity problems. Having to annotate a bunch of terms with type signatures is really anoying. Still,
students probably run into similar problems with overloaded literals, and I think, that a better approach to problems like these would be to have a simplified "learning Prelude" for the beginners class, rather than changing the standard libraries of the language (writing type signatures probably also helps...)
I don't like the idea of a learning prelude. people should teach the language outright otherwise students will end up confused. Better error messages for compilers is the correct solution, not a watered down version of the language. Once at caltech, they tried this experiment where they took the beginning programming course taught in C, and changed it to use 'java junior' a version of java for teaching, it was an absolute disaster. the students ended up not being able to program in java and not learning the basics of computer architecture that learning C gives you (as well as the ability to program in C) and generally being quite upset. IMHO everyone should know both C and Haskell fluently. there is no point dawdling in between the extremes. :) John -- John Meacham - ⑆repetae.net⑆john⑈