Gets rid of the stuff that prevents us from understanding the runtime representation of a type. Including: 1. Casts 2. Newtypes 3. Foralls 4. Synonyms But not type/data families, because we don't have the envs to hand.

True if the type has zero width.

Discovers the primitive representation of a Type. Returns a list of PrimRep: it's a list because of the possibility of no runtime representation (void) or multiple (unboxed tuple/sum)

Like typePrimRep, but assumes that there is precisely one PrimRep output; an empty list of PrimReps becomes a VoidRep

Take a type of kind RuntimeRep and extract the list of PrimRep that it encodes.

A PrimRep is an abstraction of a type. It contains information that the code generator needs in order to pass arguments, return results, and store values of this type.

Convert a PrimRep back to a Type. Used only in the unariser to give types to fresh Ids. Really, only the type's representation matters.

Find the runtime representation of a TyCon. Defined here to avoid module loops. Returns a list of the register shapes necessary.

Like tyConPrimRep, but assumed that there is precisely zero or one PrimRep output

Given the arguments of a sum type constructor application, return the unboxed sum rep type.

E.g.

( | Maybe Int | (, Float) #)

We call `ubxSumRepType [ [IntRep], [LiftedRep], [IntRep, FloatRep] ]`, which returns [WordSlot, PtrSlot, WordSlot, FloatSlot]

INVARIANT: Result slots are sorted (via Ord SlotTy), except that at the head of the list we have the slot for the tag.