Language/Symantic/Expr/Ord.hs

   1 {-# LANGUAGE DefaultSignatures #-}
   2 {-# LANGUAGE FlexibleContexts #-}
   3 {-# LANGUAGE ScopedTypeVariables #-}
   4 {-# LANGUAGE TypeFamilies #-}
   5 {-# LANGUAGE TypeOperators #-}
   6 -- | Expression for 'Ord'.
   7 module Language.Symantic.Expr.Ord where
   8
   9 import Data.Proxy (Proxy(..))
  10 import Data.Type.Equality ((:~:)(Refl))
  11 import Prelude hiding (compare)
  12
  13 import Language.Symantic.Repr.Dup
  14 import Language.Symantic.Trans.Common
  15 import Language.Symantic.Type
  16 import Language.Symantic.Expr.Common
  17 import Language.Symantic.Expr.Eq
  18
  19 -- * Class 'Sym_Ord'
  20 -- | Symantic.
  21 class Sym_Eq repr => Sym_Ord repr where
  22         compare :: Ord a => repr a -> repr a -> repr Ordering
  23         default compare :: (Trans t repr, Ord a)
  24                         => t repr a -> t repr a -> t repr Ordering
  25         compare = trans_map2 compare
  26
  27 instance (Sym_Ord r1, Sym_Ord r2) => Sym_Ord (Dup r1 r2) where
  28         compare (x1 `Dup` x2) (y1 `Dup` y2) =
  29                 compare x1 y1 `Dup`
  30                 compare x2 y2
  31
  32 -- * Type 'Expr_Ord'
  33 -- | Expression.
  34 data Expr_Ord (root:: *)
  35 type instance Root_of_Expr      (Expr_Ord root)      = root
  36 type instance Type_of_Expr      (Expr_Ord root)      = No_Type
  37 type instance Sym_of_Expr       (Expr_Ord root) repr = (Sym_Ord repr)
  38 type instance Error_of_Expr ast (Expr_Ord root)      = No_Error_Expr
  39
  40 compare_from
  41  :: forall root ty ast hs ret.
  42  ( ty ~ Type_Root_of_Expr (Expr_Ord root)
  43  , Type_Root_Lift Type_Ordering (Type_Root_of_Expr root)
  44  , Type_Eq (Type_Root_of_Expr root)
  45  , Expr_from ast root
  46  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
  47                    (Error_of_Expr ast root)
  48  , Root_of_Expr root ~ root
  49  , Type_Constraint Ord ty
  50  ) => ast -> ast
  51  -> Expr_From ast (Expr_Ord root) hs ret
  52 compare_from ast_x ast_y ex ast ctx k =
  53         expr_from (Proxy::Proxy root) ast_x ctx $
  54          \(ty_x::Type_Root_of_Expr root h_x) (Forall_Repr_with_Context x) ->
  55         expr_from (Proxy::Proxy root) ast_y ctx $
  56          \(ty_y::Type_Root_of_Expr root h_y) (Forall_Repr_with_Context y) ->
  57         check_type_eq ex ast ty_x ty_y $ \Refl ->
  58         check_type_constraint ex (Proxy::Proxy Ord) ast ty_x $ \Dict ->
  59                 k type_ordering $ Forall_Repr_with_Context $
  60                  \c -> x c `compare` y c