Language/Symantic/Compiling/Unit.hs

   1 {-# LANGUAGE UndecidableInstances #-}
   2 {-# OPTIONS_GHC -fno-warn-orphans #-}
   3 {-# OPTIONS_GHC -fconstraint-solver-iterations=5 #-}
   4 -- | Symantic for '()'.
   5 module Language.Symantic.Compiling.Unit where
   6
   7 import qualified Data.Function as Fun
   8 import Data.Monoid
   9 import Data.Proxy
  10 import Data.Text (Text)
  11 import Data.Type.Equality ((:~:)(Refl))
  12 import Prelude hiding ((&&), not, (||))
  13
  14 import Language.Symantic.Parsing
  15 import Language.Symantic.Typing
  16 import Language.Symantic.Compiling.Term
  17 import Language.Symantic.Interpreting
  18 import Language.Symantic.Transforming.Trans
  19
  20 -- * Class 'Sym_Unit'
  21 class Sym_Unit term where
  22         unit :: term ()
  23         default unit :: Trans t term => t term ()
  24         unit = trans_lift unit
  25
  26 type instance Sym_of_Iface (Proxy ()) = Sym_Unit
  27 type instance Consts_of_Iface (Proxy ()) = Proxy () ': Consts_imported_by ()
  28 type instance Consts_imported_by () =
  29  [ Proxy Bounded
  30  , Proxy Enum
  31  , Proxy Eq
  32  , Proxy Monoid
  33  , Proxy Ord
  34  , Proxy Show
  35  ]
  36
  37 instance Sym_Unit HostI where
  38         unit = HostI ()
  39 instance Sym_Unit TextI where
  40         unit = TextI $ \_p _v -> "()"
  41 instance (Sym_Unit r1, Sym_Unit r2) => Sym_Unit (DupI r1 r2) where
  42         unit = unit `DupI` unit
  43
  44 instance Const_from Text cs => Const_from Text (Proxy () ': cs) where
  45         const_from "()" k = k (ConstZ kind)
  46         const_from s k = const_from s $ k . ConstS
  47 instance Show_Const cs => Show_Const (Proxy () ': cs) where
  48         show_const ConstZ{} = "()"
  49         show_const (ConstS c) = show_const c
  50
  51 instance -- Proj_ConC
  52  ( Proj_Const cs ()
  53  , Proj_Consts cs (Consts_imported_by ())
  54  ) => Proj_ConC cs (Proxy ()) where
  55         proj_conC _ (TyConst q :$ TyConst c)
  56          | Just Refl <- eq_skind (kind_of_const c) SKiType
  57          , Just Refl <- proj_const c (Proxy::Proxy ())
  58          = case () of
  59                  _ | Just Refl <- proj_const q (Proxy::Proxy Bounded) -> Just Con
  60                    | Just Refl <- proj_const q (Proxy::Proxy Enum)    -> Just Con
  61                    | Just Refl <- proj_const q (Proxy::Proxy Eq)      -> Just Con
  62                    | Just Refl <- proj_const q (Proxy::Proxy Monoid)  -> Just Con
  63                    | Just Refl <- proj_const q (Proxy::Proxy Ord)     -> Just Con
  64                    | Just Refl <- proj_const q (Proxy::Proxy Show)    -> Just Con
  65                  _ -> Nothing
  66         proj_conC _c _q = Nothing
  67 data instance TokenT meta (ts::[*]) (Proxy ())
  68  = Token_Term_Unit
  69 deriving instance Eq_Token meta ts => Eq (TokenT meta ts (Proxy ()))
  70 deriving instance Show_Token meta ts => Show (TokenT meta ts (Proxy ()))
  71 instance -- CompileI
  72  ( Inj_Const (Consts_of_Ifaces is) ()
  73  ) => CompileI is (Proxy ()) where
  74         compileI tok _ctx k =
  75                 case tok of
  76                  Token_Term_Unit -> k (ty @()) $ TermO $ Fun.const unit