Hi all, I've been doing some work with the GHC API where I translate Haskell to VHDL, and as such I have to translate Haskell Types to VHDL Types. I store the translations in a Map as such: -- A orderable equivalent of CoreSyn's Type for use as a map key newtype OrdType = OrdType { getType :: Type.Type } instance Eq OrdType where (OrdType a) == (OrdType b) = Type.tcEqType a b instance Ord OrdType where compare (OrdType a) (OrdType b) = Type.tcCmpType a b -- A map of a Core type to the corresponding type name type TypeMap = Map.Map OrdType (AST.VHDLId, Either AST.TypeDef AST.SubtypeIn) This solution work fine for 'simple' types and ensures that the VHDL Type definitions are all unique. However, a problem rises when type operators come in to play, as Type.tcEqType does not know the 'rules' of these type operators and can thus not infer that two types are equal. Let me give some context for my problem: We use statically fixed-size vectors instead of lists, as we always want to know the static length of an array. We use a vector implementation similar to Data.Param.FSVec defined in the parameterized-data package [1], except that we use type-level integers from the tfp library [2] to define the static vector lenght. The tfp library support things like type-level multiplication, something that we use in our vector library. Now, say we have two bit vectors of length 12 defined as such: a :: Vector D12 Bit b :: Vector (D3 :*: D4) Bit The GHC type checker can infer that 'a' and 'b' are of equal type, as it knows the definitions for the ':*:' multiplication type-operator that is defined in the tfp library. Of course, the only answer Type.tcEqType can give us if we ask if the types of 'a' and 'b' are equals is False, as it does not know the context provided by the type-operator. So my question is: Is there a functions in the GHC API that I can use to check the equality of two types given the context provided by certain type operators? I have looked at the Haddock documentation, the GHC Wiki, and the GHC code itself, but have been unable to find such a function. Regards, Christiaan [1] http://hackage.haskell.org/package/parameterized-data [2] http://hackage.haskell.org/package/tfp