-- |

module Language.PureScript.CoreFn.Expr where

import Prelude.Compat

import Control.Arrow ((***))

import Language.PureScript.AST.Literals

import Language.PureScript.CoreFn.Binders

import Language.PureScript.Names

import Language.PureScript.PSString (PSString)

-- |

data Expr a

-- |

-- A literal value

--

= Literal a (Literal (Expr a))

-- |

-- A data constructor (type name, constructor name, field names)

--

| Constructor a (ProperName 'TypeName) (ProperName 'ConstructorName) [Ident]

-- |

-- A record property accessor

--

| Accessor a PSString (Expr a)

-- |

-- Partial record update

--

| ObjectUpdate a (Expr a) [(PSString, Expr a)]

-- |

-- Function introduction

--

| Abs a Ident (Expr a)

-- |

-- Function application

--

| App a (Expr a) (Expr a)

-- |

-- Variable

--

| Var a (Qualified Ident)

-- |

-- A case expression

--

| Case a [Expr a] [CaseAlternative a]

-- |

-- A let binding

--

| Let a [Bind a] (Expr a)

deriving (Show, Functor)

-- |

data Bind a

-- |

-- Non-recursive binding for a single value

--

= NonRec a Ident (Expr a)

-- |

-- Mutually recursive binding group for several values

--

| Rec [((a, Ident), Expr a)] deriving (Show, Functor)

-- |

type Guard a = Expr a

-- |

data CaseAlternative a = CaseAlternative

{ -- |

-- A collection of binders with which to match the inputs

--

caseAlternativeBinders :: [Binder a]

-- |

-- The result expression or a collect of guarded expressions

--

, caseAlternativeResult :: Either [(Guard a, Expr a)] (Expr a)

} deriving (Show)

instance Functor CaseAlternative where

fmap f (CaseAlternative cabs car) = CaseAlternative

(fmap (fmap f) cabs)

(either (Left . fmap (fmap f *** fmap f)) (Right . fmap f) car)

-- |

extractAnn :: Expr a -> a

extractAnn (Literal a _) = a

extractAnn (Constructor a _ _ _) = a

extractAnn (Accessor a _ _) = a

extractAnn (ObjectUpdate a _ _) = a

extractAnn (Abs a _ _) = a

extractAnn (App a _ _) = a

extractAnn (Var a _) = a

extractAnn (Case a _ _) = a

extractAnn (Let a _ _) = a

-- |

modifyAnn :: (a -> a) -> Expr a -> Expr a

modifyAnn f (Literal a b) = Literal (f a) b

modifyAnn f (Constructor a b c d) = Constructor (f a) b c d

modifyAnn f (Accessor a b c) = Accessor (f a) b c

modifyAnn f (ObjectUpdate a b c) = ObjectUpdate (f a) b c

modifyAnn f (Abs a b c) = Abs (f a) b c

modifyAnn f (App a b c) = App (f a) b c

modifyAnn f (Var a b) = Var (f a) b

modifyAnn f (Case a b c) = Case (f a) b c

modifyAnn f (Let a b c) = Let (f a) b c