Language/Symantic/Expr/Ord.hs

   1 {-# LANGUAGE DefaultSignatures #-}
   2 {-# LANGUAGE FlexibleContexts #-}
   3 {-# LANGUAGE ScopedTypeVariables #-}
   4 {-# LANGUAGE TypeFamilies #-}
   5 -- | Expression for 'Ord'.
   6 module Language.Symantic.Expr.Ord where
   7
   8 import Data.Proxy (Proxy(..))
   9 import Data.Type.Equality ((:~:)(Refl))
  10 import Prelude hiding (compare)
  11
  12 import Language.Symantic.Repr.Dup
  13 import Language.Symantic.Trans.Common
  14 import Language.Symantic.Type
  15 import Language.Symantic.Expr.Common
  16 import Language.Symantic.Expr.Lambda
  17 import Language.Symantic.Expr.Bool
  18 import Language.Symantic.Expr.Eq
  19
  20 -- * Class 'Sym_Ord'
  21 -- | Symantic.
  22 class Sym_Eq repr => Sym_Ord repr where
  23         compare :: Ord a => repr a -> repr a -> repr Ordering
  24         default compare :: (Trans t repr, Ord a)
  25                         => t repr a -> t repr a -> t repr Ordering
  26         compare = trans_map2 compare
  27
  28 instance (Sym_Ord r1, Sym_Ord r2) => Sym_Ord (Dup r1 r2) where
  29         compare (x1 `Dup` x2) (y1 `Dup` y2) =
  30                 compare x1 y1 `Dup`
  31                 compare x2 y2
  32
  33 -- * Type 'Expr_Ord'
  34 -- | Expression.
  35 data Expr_Ord (root:: *)
  36 type instance Root_of_Expr      (Expr_Ord root)      = root
  37 type instance Type_of_Expr      (Expr_Ord root)      = No_Type
  38 type instance Sym_of_Expr       (Expr_Ord root) repr = (Sym_Ord repr)
  39 type instance Error_of_Expr ast (Expr_Ord root)      = No_Error_Expr
  40
  41 ord_from
  42  :: forall root ty ast hs ret.
  43  ( ty ~ Type_Root_of_Expr (Expr_Ord root)
  44  , Type_Root_Lift Type_Bool     (Type_Root_of_Expr root)
  45  , Type_Root_Lift Type_Ordering (Type_Root_of_Expr root)
  46  , Type_Eq (Type_Root_of_Expr root)
  47  , Expr_from ast root
  48  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
  49                    (Error_of_Expr ast root)
  50  , Root_of_Expr root ~ root
  51  , Type_Constraint Ord ty
  52  ) => ast -> ast
  53  -> Expr_From ast (Expr_Ord root) hs ret
  54 ord_from ast_x ast_y ex ast ctx k =
  55         expr_from (Proxy::Proxy root) ast_x ctx $
  56          \(ty_x::Type_Root_of_Expr root h_x) (Forall_Repr_with_Context x) ->
  57         expr_from (Proxy::Proxy root) ast_y ctx $
  58          \(ty_y::Type_Root_of_Expr root h_y) (Forall_Repr_with_Context y) ->
  59         when_type_eq ex ast ty_x ty_y $ \Refl ->
  60         when_type_constraint ex (Proxy::Proxy Ord) ast ty_x $ \Dict ->
  61                 k type_ordering $ Forall_Repr_with_Context $
  62                  \c -> x c `compare` y c
  63
  64 -- ** Type 'Expr_Lambda_Bool_Ord'
  65 -- | Convenient alias.
  66 type Expr_Lambda_Bool_Ord lam
  67  = Expr_Root (Expr_Alt (Expr_Lambda lam)
  68              (Expr_Alt Expr_Bool
  69                        Expr_Ord))
  70
  71 -- | Convenient alias around 'expr_from'.
  72 expr_lambda_bool_ord_from
  73  :: forall lam ast.
  74  Expr_from ast (Expr_Lambda_Bool_Ord lam)
  75  => Proxy lam
  76  -> ast
  77  -> Either (Error_of_Expr ast (Expr_Lambda_Bool_Ord lam))
  78            (Exists_Type_and_Repr (Type_Root_of_Expr (Expr_Lambda_Bool_Ord lam))
  79                                  (Forall_Repr (Expr_Lambda_Bool_Ord lam)))
  80 expr_lambda_bool_ord_from _lam ast =
  81         expr_from (Proxy::Proxy (Expr_Lambda_Bool_Ord lam)) ast
  82          Context_Empty $ \ty (Forall_Repr_with_Context repr) ->
  83                 Right $ Exists_Type_and_Repr ty $
  84                         Forall_Repr $ repr Context_Empty