churf/src/Desugar/Desugar.hs

93 lines
2.8 KiB
Haskell

{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
module Desugar.Desugar (desugar) where
import Data.Function (on)
import Debug.Trace (traceShow)
import Grammar.Abs
import Grammar.Print
{-
The entire module should never have any catch all pattern matches as that
will disble warnings for when the grammar is expanded.
-}
desugar :: Program -> Program
desugar (Program defs) = Program (map desugarDef defs)
desugarVarName :: VarName -> LIdent
desugarVarName (VSymbol (Symbol i)) = LIdent i
desugarVarName (VIdent i) = i
desugarDef :: Def -> Def
desugarDef = \case
DBind b -> DBind (desugarBind b)
DSig sig -> DSig (desugarSig sig)
DData d -> DData (desugarData d)
desugarBind :: Bind -> Bind
desugarBind (BindS name args e) = Bind (desugarVarName name) args (desugarExp e)
desugarBind (Bind name args e) = Bind name args (desugarExp e)
desugarSig :: Sig -> Sig
desugarSig (SigS ident typ) = Sig (desugarVarName ident) (desugarType typ)
desugarSig (Sig ident typ) = Sig ident (desugarType typ)
desugarData :: Data -> Data
desugarData (Data typ injs) = Data (desugarType typ) (map desugarInj injs)
desugarType :: Type -> Type
desugarType = \case
TIdent (UIdent "Int") -> TLit "Int"
TIdent (UIdent "Char") -> TLit "Char"
TIdent ident -> TData ident []
TApp t1 t2 ->
let (name : tvars) = flatten t1 ++ [t2]
in case name of
TIdent ident -> TData ident (map desugarType tvars)
_ -> error "desugarType in Desugar.hs is not implemented correctly"
TLit l -> TLit l
TVar v -> TVar v
(TAll i t) -> TAll i (desugarType t)
TFun t1 t2 -> TFun (desugarType t1) (desugarType t2)
TEVar v -> TEVar v
TData ident typ -> TData ident (map desugarType typ)
where
flatten :: Type -> [Type]
flatten (TApp a b) = flatten a <> flatten b
flatten a = [a]
desugarInj :: Inj -> Inj
desugarInj (Inj ident typ) = Inj ident (desugarType typ)
desugarExp :: Exp -> Exp
desugarExp = \case
EApp e1 e2 -> EApp (desugarExp e1) (desugarExp e2)
EAdd e1 e2 -> EAdd (desugarExp e1) (desugarExp e2)
EAbs i e -> EAbs i (desugarExp e)
ELet b e -> ELet (desugarBind b) (desugarExp e)
ECase e br -> ECase (desugarExp e) (map desugarBranch br)
EAnn e t -> EAnn (desugarExp e) t
EVarS (VSymbol (Symbol symb)) -> EVar (LIdent symb)
EVarS (VIdent ident) -> EVar ident
EVar i -> EVar i
ELit l -> ELit l
EInj i -> EInj i
desugarBranch :: Branch -> Branch
desugarBranch (Branch p e) = Branch (desugarPattern p) (desugarExp e)
desugarPattern :: Pattern -> Pattern
desugarPattern = \case
PVar ident -> PVar ident
PLit lit -> PLit (desugarLit lit)
PCatch -> PCatch
PEnum ident -> PEnum ident
PInj ident patterns -> PInj ident (map desugarPattern patterns)
desugarLit :: Lit -> Lit
desugarLit (LInt i) = LInt i
desugarLit (LChar c) = LChar c