Copyright	(c) The GHC Team, 1997-2000 (c) Niklas Broberg, 2004-2012
License	BSD-style (see the file LICENSE.txt)
Maintainer	Niklas Broberg, niklas.broberg@chalmers.se
Stability	stable
Portability	portable
Safe Haskell	None
Language	Haskell98

Language.Haskell.Exts.Parser

Contents

General parsing
Parsing of specific AST elements
Non-greedy parsers
- Module head parsers

Description

Parser for Haskell with extensions.

Synopsis

General parsing

class Parseable ast where

Class providing function for parsing at many different types.

Note that for convenience of implementation, the default methods have definitions equivalent to undefined. The minimal definition is all of the visible methods.

Minimal complete definition

parser

Methods

parse :: String -> ParseResult ast

Parse a string with default mode.

parseWithMode :: ParseMode -> String -> ParseResult ast

Parse a string with an explicit ParseMode.

parseWithComments :: ParseMode -> String -> ParseResult (ast, [Comment])

Parse a string with an explicit ParseMode, returning all comments along with the AST.

data ParseMode

Static parameters governing a parse. Note that the various parse functions in Language.Haskell.Exts.Parser never look at LANGUAGE pragmas, regardless of what the ignoreLanguagePragmas flag is set to. Only the various parseFile functions in Language.Haskell.Exts will act on it, when set to False.

Constructors

ParseMode

Fields

parseFilename :: String: original name of the file being parsed
baseLanguage :: Language: base language (e.g. Haskell98, Haskell2010)
extensions :: [Extension]: list of extensions enabled for parsing
ignoreLanguagePragmas :: Bool: if True, the parser won't care about further extensions in LANGUAGE pragmas in source files
ignoreLinePragmas :: Bool: if True, the parser won't read line position information from LINE pragmas in source files
fixities :: Maybe [Fixity]: list of fixities to be aware of
ignoreFunctionArity :: Bool: Checks whether functions have a consistent arity

defaultParseMode :: ParseMode

Default parameters for a parse. The default is an unknown filename, no extensions (i.e. Haskell 98), don't ignore LANGUAGE pragmas, do ignore LINE pragmas, and be aware of fixities from the Prelude.

data ParseResult a

The result of a parse.

Constructors

ParseOk a	The parse succeeded, yielding a value.
ParseFailed SrcLoc String	The parse failed at the specified source location, with an error message.

Instances

Monad ParseResult
Functor ParseResult
Applicative ParseResult
Show a => Show (ParseResult a)
Monoid m => Monoid (ParseResult m)

fromParseResult :: ParseResult a -> a

Retrieve the result of a successful parse, throwing an error if the parse is actually not successful.

Parsing of specific AST elements

Modules

parseModule :: String -> ParseResult Module

Parse of a string, which should contain a complete Haskell module, using defaultParseMode.

parseModuleWithMode :: ParseMode -> String -> ParseResult Module

Parse of a string containing a complete Haskell module, using an explicit ParseMode.

parseModuleWithComments :: ParseMode -> String -> ParseResult (Module, [Comment])

Parse of a string containing a complete Haskell module, using an explicit ParseMode, retaining comments.

Expressions

parseExp :: String -> ParseResult Exp

Parse of a string containing a Haskell expression, using defaultParseMode.

parseExpWithMode :: ParseMode -> String -> ParseResult Exp

Parse of a string containing a Haskell expression, using an explicit ParseMode.

parseExpWithComments :: ParseMode -> String -> ParseResult (Exp, [Comment])

Parse of a string containing a complete Haskell module, using an explicit ParseMode, retaining comments.

Statements

parseStmt :: String -> ParseResult Stmt

Parse of a string containing a Haskell type, using defaultParseMode.

parseStmtWithMode :: ParseMode -> String -> ParseResult Stmt

Parse of a string containing a Haskell type, using an explicit ParseMode.

parseStmtWithComments :: ParseMode -> String -> ParseResult (Stmt, [Comment])

Parse of a string containing a complete Haskell module, using an explicit ParseMode, retaining comments.

Patterns

parsePat :: String -> ParseResult Pat

Parse of a string containing a Haskell pattern, using defaultParseMode.

parsePatWithMode :: ParseMode -> String -> ParseResult Pat

Parse of a string containing a Haskell pattern, using an explicit ParseMode.

parsePatWithComments :: ParseMode -> String -> ParseResult (Pat, [Comment])

Parse of a string containing a complete Haskell module, using an explicit ParseMode, retaining comments.

Declarations

parseDecl :: String -> ParseResult Decl

Parse of a string containing a Haskell top-level declaration, using defaultParseMode

parseDeclWithMode :: ParseMode -> String -> ParseResult Decl

Parse of a string containing a Haskell top-level declaration, using an explicit ParseMode.

parseDeclWithComments :: ParseMode -> String -> ParseResult (Decl, [Comment])

Parse of a string containing a complete Haskell module, using an explicit ParseMode, retaining comments.

Types

parseType :: String -> ParseResult Type

Parse of a string containing a Haskell type, using defaultParseMode.

parseTypeWithMode :: ParseMode -> String -> ParseResult Type

Parse of a string containing a Haskell type, using an explicit ParseMode.

parseTypeWithComments :: ParseMode -> String -> ParseResult (Type, [Comment])

Parse of a string containing a complete Haskell module, using an explicit ParseMode, retaining comments.

Import declarations

parseImportDecl :: String -> ParseResult ImportDecl

Parse of a string containing a Haskell import declaration, using defaultParseMode.

parseImportDeclWithMode :: ParseMode -> String -> ParseResult ImportDecl

Parse of a string containing a Haskell type, using an explicit ParseMode.

parseImportDeclWithComments :: ParseMode -> String -> ParseResult (ImportDecl, [Comment])

Parse of a string containing a complete Haskell module, using an explicit ParseMode, retaining comments.

Non-greedy parsers

newtype NonGreedy a

Instances of Parseable for NonGreedy a will only consume the input until a is fully parsed. This means that parse errors that come later in the input will be ignored. It's also more efficient, as it's fully lazy in the remainder of the input:

>>> parse (unlines ("module A where" : "main =" : repeat "blah")) :: ParseResult PragmasAndModuleHead
ParseOk (NonGreedy {unNonGreedy = PragmasAndModuleHead [] (ModuleName "A",Nothing,Nothing)})

(this example uses the simplified AST)

Constructors

NonGreedy
Fields unNonGreedy :: a

Instances

Functor NonGreedy
Eq a => Eq (NonGreedy a)
Data a => Data (NonGreedy a)
Ord a => Ord (NonGreedy a)
Show a => Show (NonGreedy a)
Parseable (NonGreedy (ListOf (ModulePragma SrcSpanInfo)))
Parseable (NonGreedy (ModuleHeadAndImports SrcSpanInfo))
Parseable (NonGreedy (PragmasAndModuleHead SrcSpanInfo))
Parseable (NonGreedy (PragmasAndModuleName SrcSpanInfo))
Parseable (NonGreedy ModuleHeadAndImports)
Parseable (NonGreedy PragmasAndModuleHead)
Parseable (NonGreedy PragmasAndModuleName)

Module head parsers

getTopPragmas :: String -> ParseResult [ModulePragma]

Partial parse of a string starting with a series of top-level option pragmas.

data PragmasAndModuleName

Type intended to be used with Parseable, with instances that implement a non-greedy parse of the module name, including top-level pragmas. This means that a parse error that comes after the module header won't be returned. If no module name is found (and no parse error occurs), then "Main" is returned. This is the same behavior that parseModule has.

Constructors

PragmasAndModuleName [ModulePragma] ModuleName

Instances

Eq PragmasAndModuleName
Data PragmasAndModuleName
Ord PragmasAndModuleName
Show PragmasAndModuleName
Parseable (NonGreedy PragmasAndModuleName)

data PragmasAndModuleHead

Type intended to be used with Parseable, with instances that implement a non-greedy parse of the module name, including top-level pragmas. This means that a parse error that comes after the module header won't be returned. If no module head is found, then a default simple head like "module Main where" is assumed. This is the same behavior that parseModule has.

Note that the ParseMode particularly matters for this due to the MagicHash changing the lexing of identifiers to include "#".

Constructors

PragmasAndModuleHead [ModulePragma] (ModuleName, Maybe WarningText, Maybe [ExportSpec])

Instances

Eq PragmasAndModuleHead
Data PragmasAndModuleHead
Ord PragmasAndModuleHead
Show PragmasAndModuleHead
Parseable (NonGreedy PragmasAndModuleHead)

data ModuleHeadAndImports

Type intended to be used with Parseable, with instances that implement a non-greedy parse of the module head, including top-level pragmas, module name, export list, and import list. This means that if a parse error that comes after the imports won't be returned. If no module head is found, then a default simple head like "module Main where" is assumed. This is the same behavior that parseModule has.

Note that the ParseMode particularly matters for this due to the MagicHash changing the lexing of identifiers to include "#".

Constructors

ModuleHeadAndImports [ModulePragma] (ModuleName, Maybe WarningText, Maybe [ExportSpec]) [ImportDecl]

Instances

Eq ModuleHeadAndImports
Data ModuleHeadAndImports
Ord ModuleHeadAndImports
Show ModuleHeadAndImports
Parseable (NonGreedy ModuleHeadAndImports)