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_ = repr_dup3 sym_If if_
  41
  42 sym_If :: Proxy Sym_If
  43 sym_If = Proxy
  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 2 in
  57                         paren p p' $
  58                         "when " <> cond p' v <>
  59                         " " <> ok p' v
  60 instance (Sym_When r1, Sym_When r2) => Sym_When (Repr_Dup r1 r2) where
  61         when = repr_dup2 sym_When when
  62
  63 sym_When :: Proxy Sym_When
  64 sym_When = Proxy
  65
  66 -- * Type 'Expr_If'
  67 -- | Expression.
  68 data Expr_If (root:: *)
  69 type instance Root_of_Expr      (Expr_If root)      = root
  70 type instance Type_of_Expr      (Expr_If root)      = No_Type
  71 type instance Sym_of_Expr       (Expr_If root) repr = Sym_If repr
  72 type instance Error_of_Expr ast (Expr_If root)      = No_Error_Expr
  73
  74 if_from
  75  :: forall root ty ast hs ret.
  76  ( ty ~ Type_Root_of_Expr (Expr_If root)
  77  , Type0_Eq ty
  78  , Type0_Lift Type_Bool (Type_of_Expr root)
  79  , Expr_From ast root
  80  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
  81                    (Error_of_Expr ast root)
  82  , Root_of_Expr root ~ root
  83  ) => ast -> ast -> ast
  84  -> ExprFrom ast (Expr_If root) hs ret
  85 if_from ast_cond ast_ok ast_ko ex ast ctx k =
  86         expr_from (Proxy::Proxy root) ast_cond ctx $
  87          \(ty_cond::ty h_n) (Forall_Repr_with_Context cond) ->
  88         expr_from (Proxy::Proxy root) ast_ok ctx $
  89          \(ty_ok::ty h_ok) (Forall_Repr_with_Context ok) ->
  90         expr_from (Proxy::Proxy root) ast_ko ctx $
  91          \(ty_ko::ty h_ko) (Forall_Repr_with_Context ko) ->
  92         check_type0_eq ex ast type_bool ty_cond $ \Refl ->
  93         check_type0_eq ex ast ty_ok ty_ko $ \Refl ->
  94         k ty_ok $ Forall_Repr_with_Context $
  95          \c -> if_ (cond c) (ok c) (ko c)
  96
  97 -- * Type 'Expr_When'
  98 -- | Expression.
  99 data Expr_When (root:: *)
 100 type instance Root_of_Expr      (Expr_When root)      = root
 101 type instance Type_of_Expr      (Expr_When root)      = No_Type
 102 type instance Sym_of_Expr       (Expr_When root) repr = Sym_When repr
 103 type instance Error_of_Expr ast (Expr_When root)      = No_Error_Expr
 104
 105 when_from
 106  :: forall root ty ast hs ret.
 107  ( ty ~ Type_Root_of_Expr (Expr_When root)
 108  , Type0_Eq ty
 109  , Type0_Lift Type_Bool (Type_of_Expr root)
 110  , Type0_Lift Type_Unit (Type_of_Expr root)
 111  , Expr_From ast root
 112  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
 113                    (Error_of_Expr ast root)
 114  , Root_of_Expr root ~ root
 115  ) => ast -> ast
 116  -> ExprFrom ast (Expr_When root) hs ret
 117 when_from ast_cond ast_ok ex ast ctx k =
 118         expr_from (Proxy::Proxy root) ast_cond ctx $
 119          \(ty_cond::ty h_n) (Forall_Repr_with_Context cond) ->
 120         expr_from (Proxy::Proxy root) ast_ok ctx $
 121          \(ty_ok::ty h_ok) (Forall_Repr_with_Context ok) ->
 122         check_type0_eq ex ast type_bool ty_cond $ \Refl ->
 123         check_type0_eq ex ast type_unit ty_ok $ \Refl ->
 124         k ty_ok $ Forall_Repr_with_Context $
 125          \c -> when (cond c) (ok c)