Language/Symantic/Expr/If.hs

   1 {-# LANGUAGE DefaultSignatures #-}
   2 {-# LANGUAGE FlexibleContexts #-}
   3 {-# LANGUAGE OverloadedStrings #-}
   4 {-# LANGUAGE ScopedTypeVariables #-}
   5 {-# LANGUAGE TypeFamilies #-}
   6 {-# LANGUAGE TypeOperators #-}
   7 -- | Expression for @if@.
   8 module Language.Symantic.Expr.If where
   9
  10 import qualified Control.Monad as Monad
  11 import Data.Monoid
  12 import Data.Proxy (Proxy(..))
  13 import Data.Type.Equality ((:~:)(Refl))
  14
  15 import Language.Symantic.Type
  16 import Language.Symantic.Repr
  17 import Language.Symantic.Expr.Root
  18 import Language.Symantic.Expr.Error
  19 import Language.Symantic.Expr.From
  20 import Language.Symantic.Trans.Common
  21
  22 -- * Class 'Sym_If'
  23 -- | Symantic.
  24 class Sym_If repr where
  25         if_  :: repr Bool -> repr a -> repr a -> repr a
  26         default if_ :: Trans t repr => t repr Bool -> t repr a -> t repr a -> t repr a
  27         if_  = trans_map3 if_
  28 instance Sym_If Repr_Host where
  29         if_ (Repr_Host b) ok ko = if b then ok else ko
  30 instance Sym_If Repr_Text where
  31         if_ (Repr_Text cond) (Repr_Text ok) (Repr_Text ko) =
  32                 Repr_Text $ \p v ->
  33                         let p' = precedence_If in
  34                         paren p p' $
  35                         "if " <> cond p' v <>
  36                         " then " <> ok p' v <>
  37                         " else " <> ko p' v
  38 instance
  39  ( Sym_If r1
  40  , Sym_If r2
  41  ) => Sym_If (Dup r1 r2) where
  42         if_ (c1 `Dup` c2) (ok1 `Dup` ok2) (ko1 `Dup` ko2) =
  43                 if_ c1 ok1 ko1 `Dup` if_ c2 ok2 ko2
  44
  45 -- * Class 'Sym_When'
  46 -- | Symantic.
  47 class Sym_When repr where
  48         when :: repr Bool -> repr () -> repr ()
  49         default when :: Trans t repr => t repr Bool -> t repr () -> t repr ()
  50         when = trans_map2 when
  51 instance Sym_When Repr_Host where
  52         when (Repr_Host b) = Monad.when b
  53 instance Sym_When Repr_Text where
  54         when (Repr_Text cond) (Repr_Text ok) =
  55                 Repr_Text $ \p v ->
  56                         let p' = precedence_If in
  57                         paren p p' $
  58                         "when " <> cond p' v <>
  59                         " " <> ok p' v
  60 instance
  61  ( Sym_When r1
  62  , Sym_When r2
  63  ) => Sym_When (Dup r1 r2) where
  64         when (c1 `Dup` c2) (ok1 `Dup` ok2) =
  65                 when c1 ok1 `Dup` when c2 ok2
  66
  67 -- * Type 'Expr_If'
  68 -- | Expression.
  69 data Expr_If (root:: *)
  70 type instance Root_of_Expr      (Expr_If root)      = root
  71 type instance Type_of_Expr      (Expr_If root)      = No_Type
  72 type instance Sym_of_Expr       (Expr_If root) repr = (Sym_If repr)
  73 type instance Error_of_Expr ast (Expr_If root)      = No_Error_Expr
  74
  75 if_from
  76  :: forall root ty ast hs ret.
  77  ( ty ~ Type_Root_of_Expr (Expr_If root)
  78  , Eq_Type ty
  79  , Lift_Type Type_Bool (Type_of_Expr root)
  80  , Expr_from ast root
  81  , Lift_Error_Expr (Error_Expr (Error_of_Type ast ty) ty ast)
  82                    (Error_of_Expr ast root)
  83  , Root_of_Expr root ~ root
  84  ) => ast -> ast -> ast
  85  -> Expr_From ast (Expr_If root) hs ret
  86 if_from ast_cond ast_ok ast_ko ex ast ctx k =
  87         expr_from (Proxy::Proxy root) ast_cond ctx $
  88          \(ty_cond::ty h_n) (Forall_Repr_with_Context cond) ->
  89         expr_from (Proxy::Proxy root) ast_ok ctx $
  90          \(ty_ok::ty h_ok) (Forall_Repr_with_Context ok) ->
  91         expr_from (Proxy::Proxy root) ast_ko ctx $
  92          \(ty_ko::ty h_ko) (Forall_Repr_with_Context ko) ->
  93         check_eq_type ex ast type_bool ty_cond $ \Refl ->
  94         check_eq_type ex ast ty_ok ty_ko $ \Refl ->
  95         k ty_ok $ Forall_Repr_with_Context $
  96          \c -> if_ (cond c) (ok c) (ko c)
  97
  98 -- * Type 'Expr_When'
  99 -- | Expression.
 100 data Expr_When (root:: *)
 101 type instance Root_of_Expr      (Expr_When root)      = root
 102 type instance Type_of_Expr      (Expr_When root)      = No_Type
 103 type instance Sym_of_Expr       (Expr_When root) repr = (Sym_When repr)
 104 type instance Error_of_Expr ast (Expr_When root)      = No_Error_Expr
 105
 106 when_from
 107  :: forall root ty ast hs ret.
 108  ( ty ~ Type_Root_of_Expr (Expr_When root)
 109  , Eq_Type ty
 110  , Lift_Type Type_Bool (Type_of_Expr root)
 111  , Lift_Type Type_Unit (Type_of_Expr root)
 112  , Expr_from ast root
 113  , Lift_Error_Expr (Error_Expr (Error_of_Type ast ty) ty ast)
 114                    (Error_of_Expr ast root)
 115  , Root_of_Expr root ~ root
 116  ) => ast -> ast
 117  -> Expr_From ast (Expr_When root) hs ret
 118 when_from ast_cond ast_ok ex ast ctx k =
 119         expr_from (Proxy::Proxy root) ast_cond ctx $
 120          \(ty_cond::ty h_n) (Forall_Repr_with_Context cond) ->
 121         expr_from (Proxy::Proxy root) ast_ok ctx $
 122          \(ty_ok::ty h_ok) (Forall_Repr_with_Context ok) ->
 123         check_eq_type ex ast type_bool ty_cond $ \Refl ->
 124         check_eq_type ex ast type_unit ty_ok $ \Refl ->
 125         k ty_ok $ Forall_Repr_with_Context $
 126          \c -> when (cond c) (ok c)