Hi, I wrote some Template Haskell templates that I think may be of use to others. The first generates "in" and "with" functions for newtypes. For example, using it one can replace this code (from TypeCompose):

inFlip :: ((a~>b) -> (a' ~~> b')) -> (Flip (~>) b a -> Flip (~~>) b' a') inFlip = (Flip .).(. unFlip)

inFlip2 :: ((a~>b) -> (a' ~~> b') -> (a'' ~~~> b'')) -> (Flip (~>) b a -> Flip (~~>) b' a' -> Flip (~~~>) b'' a'') inFlip2 f (Flip ar) = inFlip (f ar)

inFlip3 :: ((a~>b) -> (a' ~~> b') -> (a'' ~~~> b'') -> (a''' ~~~~> b''')) -> (Flip (~>) b a -> Flip (~~>) b' a' -> Flip (~~~>) b'' a'' -> Flip (~~~~>) b''' a''') inFlip3 f (Flip ar) = inFlip2 (f ar)

with this code:

{-# LANGUAGE TemplateHaskell #-} import Data.Newtype $(mkInNewtypeFuncs [1..3] ''Flip)

The second template is for accessing ADTs in the Maybe monad. For example:

{-# LANGUAGE TemplateHaskell #-} import Data.ADT.Getters data Blah a = NoBlah | YesBlah a | ManyBlah a Int $(mkADTGetters ''Blah)

Generates:

gNoBlah :: Blah a -> Maybe () gYesBlah :: Blah a -> Maybe a gManyBlah :: Blah a -> Maybe (a, Int)

I'm more than willing to upload these templates to hackage (or rather, split them out of an unrelated package), but all I need is a suggestion for a package name :) For now you can find these here: http://hackage.haskell.org/package/peakachu Hoping someone else will find it useful, cheers, Yair