All,
2010/12/27 Jonathan Geddes
I see TH used most for the following tasks:
#1 Parse a string at compile-time so that a custom syntax for representing data can be used. At the extreme, this "data" might even be an EDSL. #2 Provide instances automatically.
Just a note that TH is also sometimes used in its generality: as a general compile time meta-programming facility. For example, in my experimental grammar-combinators parsing library [1], I am using it to perform grammar transformations at compile time by simply generating the definition for the transformed grammar using TH. This could be extended in the future to provide a low-cost parser generator that works from within TH, which can reuse the library's infrastructure. Dominique [1] http://projects.haskell.org/grammar-combinators/