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Binders.hs
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-----------------------------------------------------------------------------
--
-- Module : Language.PureScript.AST.Binders
-- Copyright : (c) 2013-14 Phil Freeman, (c) 2014 Gary Burgess, and other contributors
-- License : MIT
--
-- Maintainer : Phil Freeman <paf31@cantab.net>
-- Stability : experimental
-- Portability :
--
-- | Case binders
--
-----------------------------------------------------------------------------
{-# LANGUAGE DeriveDataTypeable #-}
module Language.PureScript.AST.Binders where
import qualified Data.Data as D
import Language.PureScript.AST.SourcePos
import Language.PureScript.Names
import Language.PureScript.Comments
-- |
-- Data type for binders
--
data Binder
-- |
-- Wildcard binder
--
= NullBinder
-- |
-- A binder which matches a boolean literal
--
| BooleanBinder Bool
-- |
-- A binder which matches a string literal
--
| StringBinder String
-- |
-- A binder which matches a character literal
--
| CharBinder Char
-- |
-- A binder which matches a numeric literal
--
| NumberBinder (Either Integer Double)
-- |
-- A binder which binds an identifier
--
| VarBinder Ident
-- |
-- A binder which matches a data constructor
--
| ConstructorBinder (Qualified ProperName) [Binder]
-- |
-- A binder which matches a record and binds its properties
--
| ObjectBinder [(String, Binder)]
-- |
-- A binder which matches an array and binds its elements
--
| ArrayBinder [Binder]
-- |
-- A binder which binds its input to an identifier
--
| NamedBinder Ident Binder
-- |
-- A binder with source position information
--
| PositionedBinder SourceSpan [Comment] Binder deriving (Show, D.Data, D.Typeable)
-- |
-- Collect all names introduced in binders in an expression
--
binderNames :: Binder -> [Ident]
binderNames = go []
where
go ns (VarBinder name) = name : ns
go ns (ConstructorBinder _ bs) = foldl go ns bs
go ns (ObjectBinder bs) = foldl go ns (map snd bs)
go ns (ArrayBinder bs) = foldl go ns bs
go ns (NamedBinder name b) = go (name : ns) b
go ns (PositionedBinder _ _ b) = go ns b
go ns _ = ns