Definition elimination for CoreProg?

[conal]

Is there a transformation like letSubstR but for CoreProg instead of CoreExpr? Perhaps it would amount to a traversal with unfoldNameR, plus a transformation to remove unused definitions. I guess it'd have to include a check that the name is not exported.

[xich]

There isn't, but I think this would work:

{-# LANGUAGE ScopedTypeVariables #-}

progNonRecSubstR :: forall c m. Rewrite c m CoreProg
progNonRecSubstR = do
  ProgCons (NonRec v _) _ <- idR
  extractR (anybuR (promoteExprR (unfoldPredR (const . (==v))) :: Rewrite c m Core)) >>> progBindElimR

To handle recursive groups at the CoreProg level, you'd probably want a rewrite that breaks them into non-recursive bindings and SCC recursive groups. I believe GHC's occurAnalysePgm will do this (along with some other stuff), so you could lift it into a rewrite. Neil lifted the expression-level version in HERMIT.Dictionary.GHC.

[conal]

Thanks!