Hi
I'm trying to write a function:
reaches :: Type -> Q [Type]
The intention is that reaches (Either Bool [Int]) would return [Either
Bool [Int], Bool, [Int], Int] - i.e. all types which are contained by
the initial type at any level.
I took a shot at this:
getTypes :: Type -> Q [Type]
getTypes t = do
let (ConT c, cs) = typeApp t
TyConI dat <- reify c
return $ concatMap ctorTypes $ dataCtors dat
reaches :: Type -> Q [Type]
reaches t = f [] [t]
where
f done [] = return done
f done (t:odo)
| t `elem` done = f done odo
| otherwise = do
ts <- getTypes t
f (t:done) (odo ++ ts)
Where typeApp splits a type to find its constructor, ctorTypes gets
the types of the fields, and dataCtors gets the constructors in a data
type. Unfortunately reify doesn't seem to work on types. Is it
possible to do what I am after?
Thanks
Neil
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