Language/Symantic/Expr/Eq.hs

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