Language/Symantic/Expr/Eq.hs

   1 {-# LANGUAGE DefaultSignatures #-}
   2 {-# LANGUAGE FlexibleContexts #-}
   3 {-# LANGUAGE FlexibleInstances #-}
   4 {-# LANGUAGE MultiParamTypeClasses #-}
   5 {-# LANGUAGE PolyKinds #-}
   6 {-# LANGUAGE ScopedTypeVariables #-}
   7 {-# LANGUAGE TypeFamilies #-}
   8 {-# LANGUAGE TypeOperators #-}
   9 {-# LANGUAGE NoMonomorphismRestriction #-}
  10 {-# OPTIONS_GHC -fno-warn-orphans #-}
  11 -- | Expression for 'Eq'.
  12 module Language.Symantic.Expr.Eq where
  13
  14 import Data.Proxy (Proxy(..))
  15 import Data.Type.Equality ((:~:)(Refl))
  16 import Prelude hiding ((==))
  17
  18 import Language.Symantic.Trans.Common
  19 import Language.Symantic.Type
  20 import Language.Symantic.Expr.Root
  21 import Language.Symantic.Expr.Error
  22 import Language.Symantic.Expr.From
  23
  24 -- * Class 'Sym_Eq'
  25 -- | Symantic.
  26 class Sym_Eq repr where
  27         (==) :: Eq a => repr a -> repr a -> repr Bool
  28         default (==) :: (Trans t repr, Eq a)
  29                      => t repr a -> t repr a -> t repr Bool
  30         (==) = trans_map2 (==)
  31 infix 4 ==
  32
  33 -- * Type 'Expr_Eq'
  34 -- | Expression.
  35 data Expr_Eq (root:: *)
  36 type instance Root_of_Expr      (Expr_Eq root)      = root
  37 type instance Type_of_Expr      (Expr_Eq root)      = No_Type
  38 type instance Sym_of_Expr       (Expr_Eq root) repr = (Sym_Eq repr)
  39 type instance Error_of_Expr ast (Expr_Eq root)      = No_Error_Expr
  40
  41 instance Constraint_Type Eq (Type_Var0 root)
  42 instance Constraint_Type Eq (Type_Var1 root)
  43
  44 eq_from
  45  :: forall root ty ast hs ret.
  46  ( ty ~ Type_Root_of_Expr (Expr_Eq root)
  47  , Lift_Type Type_Bool (Type_of_Expr root)
  48  , Eq_Type ty
  49  , Expr_from ast root
  50  , Lift_Error_Expr (Error_Expr (Error_of_Type ast ty) ty ast)
  51                    (Error_of_Expr ast root)
  52  , Root_of_Expr root ~ root
  53  , Constraint_Type Eq ty
  54  ) => ast -> ast
  55  -> Expr_From ast (Expr_Eq root) hs ret
  56 eq_from ast_x ast_y ex ast ctx k =
  57         expr_from (Proxy::Proxy root) ast_x ctx $
  58          \(ty_x::ty h_x) (Forall_Repr_with_Context x) ->
  59         expr_from (Proxy::Proxy root) ast_y ctx $
  60          \(ty_y::ty h_y) (Forall_Repr_with_Context y) ->
  61         check_eq_type ex ast ty_x ty_y $ \Refl ->
  62         check_constraint_type ex (Proxy::Proxy Eq) ast ty_x $ \Dict ->
  63         k type_bool $ Forall_Repr_with_Context $
  64          \c -> x c == y c