-- | Make a fully applied 'foldr' expression
mkFoldrExpr :: MonadThings m
            => Type             -- ^ Element type of the list
            -> Type             -- ^ Fold result type
            -> CoreExpr         -- ^ "Cons" function expression for the fold
            -> CoreExpr         -- ^ "Nil" expression for the fold
            -> CoreExpr         -- ^ List expression being folded acress
            -> m CoreExpr
mkFoldrExpr elt_ty result_ty c n list = do
    foldr_id <- lookupId foldrName
    return (Var foldr_id `App` Type elt_ty
           `App` Type result_ty
           `App` c
           `App` n
           `App` list)

-- | Make a 'build' expression applied to a locally-bound worker function
mkFoldrExpr :: MonadThings m
            => Type             -- ^ Element type of the list
            -> Type             -- ^ Fold result type
            -> CoreExpr         -- ^ "Cons" function expression for the fold
            -> CoreExpr         -- ^ "Nil" expression for the fold
            -> CoreExpr         -- ^ List expression being folded acress
            -> m CoreExpr
mkFoldrExpr elt_ty result_ty c n list = do
    foldr_id <- lookupId foldrName
    return (Var foldr_id `App` Type elt_ty
           `App` Type result_ty
           `App` c
           `App` n
           `App` list)

-- | Make a 'build' expression applied to a locally-bound worker function
mkFoldrExpr elt_ty result_ty c n list = do
    foldr_id <- lookupId foldrName
    return (Var foldr_id `App` Type elt_ty
           `App` Type result_ty
           `App` c
           `App` n
           `App` list)

-- | Make a 'build' expression applied to a locally-bound worker function