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 2 in
  34                         paren p p' $
  35                         "if " <> cond p' v <>
  36                         " then " <> ok p' v <>
  37                         " else " <> ko p' v
  38
  39 instance (Sym_If r1, Sym_If r2) => Sym_If (Repr_Dup r1 r2) where
  40         if_ (c1 `Repr_Dup` c2) (ok1 `Repr_Dup` ok2) (ko1 `Repr_Dup` ko2) =
  41                 if_ c1 ok1 ko1 `Repr_Dup` if_ c2 ok2 ko2
  42
  43 -- * Class 'Sym_When'
  44 -- | Symantic.
  45 class Sym_When repr where
  46         when :: repr Bool -> repr () -> repr ()
  47         default when :: Trans t repr => t repr Bool -> t repr () -> t repr ()
  48         when = trans_map2 when
  49 instance Sym_When Repr_Host where
  50         when (Repr_Host b) = Monad.when b
  51 instance Sym_When Repr_Text where
  52         when (Repr_Text cond) (Repr_Text ok) =
  53                 Repr_Text $ \p v ->
  54                         let p' = Precedence 2 in
  55                         paren p p' $
  56                         "when " <> cond p' v <>
  57                         " " <> ok p' v
  58 instance (Sym_When r1, Sym_When r2) => Sym_When (Repr_Dup r1 r2) where
  59         when (c1 `Repr_Dup` c2) (ok1 `Repr_Dup` ok2) =
  60                 when c1 ok1 `Repr_Dup` when c2 ok2
  61
  62 -- * Type 'Expr_If'
  63 -- | Expression.
  64 data Expr_If (root:: *)
  65 type instance Root_of_Expr      (Expr_If root)      = root
  66 type instance Type_of_Expr      (Expr_If root)      = No_Type
  67 type instance Sym_of_Expr       (Expr_If root) repr = (Sym_If repr)
  68 type instance Error_of_Expr ast (Expr_If root)      = No_Error_Expr
  69
  70 if_from
  71  :: forall root ty ast hs ret.
  72  ( ty ~ Type_Root_of_Expr (Expr_If root)
  73  , Type0_Eq ty
  74  , Type0_Lift Type_Bool (Type_of_Expr root)
  75  , Expr_From ast root
  76  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
  77                    (Error_of_Expr ast root)
  78  , Root_of_Expr root ~ root
  79  ) => ast -> ast -> ast
  80  -> ExprFrom ast (Expr_If root) hs ret
  81 if_from ast_cond ast_ok ast_ko ex ast ctx k =
  82         expr_from (Proxy::Proxy root) ast_cond ctx $
  83          \(ty_cond::ty h_n) (Forall_Repr_with_Context cond) ->
  84         expr_from (Proxy::Proxy root) ast_ok ctx $
  85          \(ty_ok::ty h_ok) (Forall_Repr_with_Context ok) ->
  86         expr_from (Proxy::Proxy root) ast_ko ctx $
  87          \(ty_ko::ty h_ko) (Forall_Repr_with_Context ko) ->
  88         check_type0_eq ex ast type_bool ty_cond $ \Refl ->
  89         check_type0_eq ex ast ty_ok ty_ko $ \Refl ->
  90         k ty_ok $ Forall_Repr_with_Context $
  91          \c -> if_ (cond c) (ok c) (ko c)
  92
  93 -- * Type 'Expr_When'
  94 -- | Expression.
  95 data Expr_When (root:: *)
  96 type instance Root_of_Expr      (Expr_When root)      = root
  97 type instance Type_of_Expr      (Expr_When root)      = No_Type
  98 type instance Sym_of_Expr       (Expr_When root) repr = (Sym_When repr)
  99 type instance Error_of_Expr ast (Expr_When root)      = No_Error_Expr
 100
 101 when_from
 102  :: forall root ty ast hs ret.
 103  ( ty ~ Type_Root_of_Expr (Expr_When root)
 104  , Type0_Eq ty
 105  , Type0_Lift Type_Bool (Type_of_Expr root)
 106  , Type0_Lift Type_Unit (Type_of_Expr root)
 107  , Expr_From ast root
 108  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
 109                    (Error_of_Expr ast root)
 110  , Root_of_Expr root ~ root
 111  ) => ast -> ast
 112  -> ExprFrom ast (Expr_When root) hs ret
 113 when_from ast_cond ast_ok ex ast ctx k =
 114         expr_from (Proxy::Proxy root) ast_cond ctx $
 115          \(ty_cond::ty h_n) (Forall_Repr_with_Context cond) ->
 116         expr_from (Proxy::Proxy root) ast_ok ctx $
 117          \(ty_ok::ty h_ok) (Forall_Repr_with_Context ok) ->
 118         check_type0_eq ex ast type_bool ty_cond $ \Refl ->
 119         check_type0_eq ex ast type_unit ty_ok $ \Refl ->
 120         k ty_ok $ Forall_Repr_with_Context $
 121          \c -> when (cond c) (ok c)