Lennart Augustsson has a really interesting example of using GADTs and
the Maybe monad to validate an untyped AST into a typed,
(mostly-)correct-by-construction AST here:
http://augustss.blogspot.com/2009/06/more-llvm-recently-someone-asked-me-on....
This was one of my first exposures to GADTs and it set my mind racing.
I wrote a small compiler for simple scalar/vector/matrix arithmetic
expressions with variables as my first nontrivial Haskell project, and
it was heavily inspired by Lennart's article. (I can put it up online
if anyone's interested, but I'm not relishing the thought of updating
LLVM on my system and the various packages and possibly the code to
make it all work again.)
On Tue, Aug 14, 2012 at 1:32 PM, Simon Peyton-Jones
Friends
I’m giving a series of five lectures at the Laser Summer School (2-8 Sept), on “Adventures with types in Haskell”. My plan is:
1. Type classes
2. Type families [examples including Repa type tags]
3. GADTs
4. Kind polymorphism
5. System FC and deferred type errors
This message is to invite you to send me your favourite example of using a GADT to get the job done. Ideally I’d like to use examples that are (a) realistic, drawn from practice (b) compelling and (c) easy to present without a lot of background. Most academic papers only have rather limited examples, usually eval :: Term t -> t, but I know that GADTs are widely used in practice.
Any ideas from your experience, satisfying (a-c)? If so, and you can spare the time, do send me a short write-up. Copy the list, so that we can all benefit.
Many thanks
Simon
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-- Your ship was destroyed in a monadic eruption.