symantic-lib/Language/Symantic/Lib/If.hs

   1 {-# LANGUAGE UndecidableInstances #-}
   2 {-# OPTIONS_GHC -fno-warn-orphans #-}
   3 {-# OPTIONS_GHC -fconstraint-solver-iterations=5 #-}
   4 -- | Symantic for @if@.
   5 module Language.Symantic.Lib.If where
   6
   7 import Data.Proxy
   8 import Data.Type.Equality ((:~:)(Refl))
   9 import qualified Data.Text as Text
  10
  11 import Language.Symantic.Parsing
  12 import Language.Symantic.Typing
  13 import Language.Symantic.Compiling
  14 import Language.Symantic.Interpreting
  15 import Language.Symantic.Transforming
  16 import Language.Symantic.Lib.Lambda
  17
  18 -- * Class 'Sym_If'
  19 class Sym_If term where
  20         if_ :: term Bool -> term a -> term a -> term a
  21         default if_ :: Trans t term => t term Bool -> t term a -> t term a -> t term a
  22         if_ = trans_map3 if_
  23
  24 -- * Type 'If'
  25 data If
  26 type instance Sym_of_Iface (Proxy If) = Sym_If
  27 type instance TyConsts_of_Iface (Proxy If) = TyConsts_imported_by (Proxy If)
  28 type instance TyConsts_imported_by (Proxy If) = '[ Proxy Bool ]
  29
  30 instance Sym_If HostI where
  31         if_ (HostI b) ok ko = if b then ok else ko
  32 instance Sym_If TextI where
  33         if_ (TextI cond) (TextI ok) (TextI ko) =
  34                 TextI $ \po v ->
  35                         infix_paren po op $
  36                         Text.concat
  37                          [ "if ", cond (op, L) v
  38                          , " then ", ok (op, L) v
  39                          , " else ", ko (op, L) v ]
  40                 where op = infixN 2
  41 instance (Sym_If r1, Sym_If r2) => Sym_If (DupI r1 r2) where
  42         if_  = dupI3 @Sym_If if_
  43
  44 instance
  45  ( Read_TyNameR TyName cs rs
  46  ) => Read_TyNameR TyName cs (Proxy If ': rs) where
  47         read_TyNameR _rs = read_TyNameR (Proxy @rs)
  48 instance Show_TyConst cs => Show_TyConst (Proxy If ': cs) where
  49         show_TyConst TyConstZ{} = "If"
  50         show_TyConst (TyConstS c) = show_TyConst c
  51
  52 instance Proj_TyConC cs (Proxy If)
  53 data instance TokenT meta (ts::[*]) (Proxy If)
  54  = Token_Term_If_if (EToken meta ts) (EToken meta ts)
  55 deriving instance Eq_Token meta ts => Eq (TokenT meta ts (Proxy If))
  56 deriving instance Show_Token meta ts => Show (TokenT meta ts (Proxy If))
  57
  58 instance -- CompileI
  59  ( Inj_TyConst cs Bool
  60  , Inj_TyConst cs (->)
  61  , Compile cs is
  62  ) => CompileI cs is (Proxy If) where
  63         compileI tok ctx k =
  64                 case tok of
  65                  Token_Term_If_if tok_cond tok_ok ->
  66                         -- if :: Bool -> a -> a -> a
  67                         compile tok_cond ctx $ \ty_cond (Term cond) ->
  68                         compile tok_ok   ctx $ \ty_ok   (Term ok) ->
  69                         check_TyEq
  70                          (At Nothing (ty @Bool))
  71                          (At (Just tok_cond) ty_cond) $ \Refl ->
  72                         k (ty_ok ~> ty_ok) $ Term $
  73                          \c -> lam $ if_ (cond c) (ok c)
  74 instance -- TokenizeT
  75  -- Inj_Token meta ts If =>
  76  TokenizeT meta ts (Proxy If)
  77 instance Gram_Term_AtomsT meta ts (Proxy If) g -- TODO