Language.Haskell.Lexer

Documentation

type PosToken = (Token, (Pos, String))

data Token

Haskell token classifications:

Constructors

Varid

Variable

Conid

Constructor

Varsym

Variable operator

Consym

Constructor operator

Reservedid

Reserved keyword

Reservedop

Reserved operator

Specialid

IntLit

Integral numeric literal

FloatLit

Fractional numeric literal

CharLit

Character literal

StringLit

String literal

Qvarid

Qualified variable

Qconid

Qualified constructor

Qvarsym

Qualified variable operator

Qconsym

Qualified constructor operator

Special

Whitespace

White space

NestedCommentStart

Internal: causes a call to an external function

NestedComment

A nested comment ({- ... -})

LiterateComment

Not handled by the lexer

Commentstart

Dashes

Comment

The stuff after the dashes

ErrorToken

GotEOF

TheRest

ModuleName

ModuleAlias

recognized in a later pass

Layout

for implicit braces

Indent Int

<n>, to preceed first token on each line

Open Int

{n}, after let, where, do or of, if not followed by a "{"

Instances

Eq Token

Methods

(==) :: Token -> Token -> Bool

(/=) :: Token -> Token -> Bool

Ord Token

Methods

compare :: Token -> Token -> Ordering

(<) :: Token -> Token -> Bool

(<=) :: Token -> Token -> Bool

(>) :: Token -> Token -> Bool

(>=) :: Token -> Token -> Bool

max :: Token -> Token -> Token

min :: Token -> Token -> Token

Show Token

Methods

showsPrec :: Int -> Token -> ShowS

show :: Token -> String

showList :: [Token] -> ShowS

lexerPass0 :: String -> [PosToken]

Tokenize and add position information. Preserves white space, and does not insert extra tokens due to layout.

lexerPass0' :: Pos -> String -> [PosToken]

Same as lexerPass0, except that it uses the given start position.

lexerPass1 :: String -> [PosToken]

The function lexerPass1 handles the part of lexical analysis that can be done independently of the parser---the tokenization and the addition of the extra layout tokens <n> and {n}, as specified in section 9.3 of the revised Haskell 98 Report.

rmSpace :: [PosToken] -> [PosToken]

Remove token that are not meaningful (e.g., white space and comments).

layoutPre :: [PosToken] -> [PosToken]

This is an implementation of Haskell layout, as specified in section 9.3 of the revised Haskell 98 report. This preprocessor inserts the extra <n> and {n} tokens.

data Pos

The posisiotn within a file.

Constructors

Pos

Fields

• char, line, column :: !Int

Instances

Eq Pos

Methods

(==) :: Pos -> Pos -> Bool

(/=) :: Pos -> Pos -> Bool

Ord Pos

Methods

compare :: Pos -> Pos -> Ordering

(<) :: Pos -> Pos -> Bool

(<=) :: Pos -> Pos -> Bool

(>) :: Pos -> Pos -> Bool

(>=) :: Pos -> Pos -> Bool

max :: Pos -> Pos -> Pos

min :: Pos -> Pos -> Pos

Show Pos

Methods

showsPrec :: Int -> Pos -> ShowS

show :: Pos -> String

showList :: [Pos] -> ShowS

simpPos :: Pos -> (Int, Int)

The line and column numbers of a position.

startPos :: Pos

The first column is designated column 1, not 0.

nextPos :: Pos -> String -> Pos

Advance position by a string.

nextPos1 :: Pos -> Char -> Pos

Advance position by a single character.