Getting associated type synonyms with template Haskell

Question

It is not implemented because nobody requested it.

The odd thing is that TH uses its own AST, which doesn't follow internal compiler's AST. As a result, any new feature (e.g. associated type families) is not automatically available via TH. Some one have to open a ticket and implement it.

For the reference: internal reifyClass function ignores associated type families (it is the 5th element of the tuple returned by classExtraBigSig, see also definition of ClassATItem.)

Technically it should be easy to implement associated type family support in reify, but most likely it will require backward incompatible changes in TH API, e.g. because its AST doesn't seem to support associated type defaults.

Added: It is now implemented (without API change btw) and probably will be available in the next ghc release.