Language/Symantic/Expr/Ord.hs

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