I have the same problem too when using Haskell. The more I try to enforce static guarantees the more I get lots of datatypes that are similar except for one or two constructors. The best way I have found to avoid this is to simply give up on some of the static guarantees and just use one datatype that contains all the constructors. Less static guarantees but also less needless type coaxing between 90% similar types. I haven't tried using macros. On Tue, 24 Apr 2007, Joel Reymont wrote:
I'm finding myself dealing with several large abstract syntax trees that are very similar in nature. The constructor names would be the same or one type may be a small extension of another.
This is something that I wouldn't worry about with Lisp, for example, as I would create a bunch of macros for creating syntax trees and reuse them all over. I cannot do this in Haskell, though, as my "macros" are functions and so I must repeat them for every AST since they return different types.
I'm wondering if Template Haskell is a suitable replacement for Lisp macros.
What is the consensus?
Thanks, Joel
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