- newtype Parser t a = P ([t] -> (Either String a, [t]))
- runParser :: Parser t a -> [t] -> (a, [t])
- failBad :: String -> Parser t a
- commit :: Parser t a -> Parser t a
- next :: Parser t t
- satisfy :: (t -> Bool) -> Parser t t
- apply :: Parser t (a -> b) -> Parser t a -> Parser t b
- discard :: Parser t a -> Parser t b -> Parser t a
- adjustErr :: Parser t a -> (String -> String) -> Parser t a
- adjustErrBad :: Parser t a -> (String -> String) -> Parser t a
- indent :: Int -> String -> String
- onFail :: Parser t a -> Parser t a -> Parser t a
- oneOf :: [Parser t a] -> Parser t a
- oneOf' :: [(String, Parser t a)] -> Parser t a
- optional :: Parser t a -> Parser t (Maybe a)
- exactly :: Int -> Parser t a -> Parser t [a]
- many :: Parser t a -> Parser t [a]
- many1 :: Parser t a -> Parser t [a]
- sepBy :: Parser t a -> Parser t sep -> Parser t [a]
- sepBy1 :: Parser t a -> Parser t sep -> Parser t [a]
- bracketSep :: Parser t bra -> Parser t sep -> Parser t ket -> Parser t a -> Parser t [a]
- bracket :: Parser t bra -> Parser t ket -> Parser t a -> Parser t a
- manyFinally :: Parser t a -> Parser t z -> Parser t [a]
- reparse :: [t] -> Parser t ()
The Parser datatype.
When applied, these parsers do not return explicit failure.
An exception is
raised instead. This allows partial results to be returned
before a full parse is complete.
One of the key ways to ensure that your parser is properly lazy,
is to parse the initial portion of text returning a function, then
apply combinator to build the final value.
Parser datatype is a fairly generic parsing monad with error
reporting. It can be used for arbitrary token types, not just
String input. (If you require a running state, use module PolyStateLazy
Apply a parser to an input token sequence. The parser cannot return an error value explicitly, so errors raise an exception. Thus, results can be partial (lazily constructed, but containing undefined).
Simple failure can be corrected, but when a simple fail is not strong enough, use failBad for emphasis. It guarantees parsing will terminate with an exception.
Commit is a way of raising the severity of any errors found within its argument. Used in the middle of a parser definition, it means that any operations prior to commitment fail softly, but after commitment, they fail hard.
Apply a parsed function to a parsed value
x parses both x and y, but discards the result of y
p applies the transformation
f to any error message
p, having no effect if
adjustErrBad is just like
adjustErr except it also raises the
severity of the error.
Helper for formatting error messages: indents all lines by a fixed amount.
p means parse p unless p fails in which case parse q instead.
Can be chained together to give multiple attempts to parse something.
(Note that q could itself be a failing parser, e.g. to change the error
message from that defined in p to something different.)
However, a *severe* failure in p cannot be ignored.
Parse the first alternative that succeeds, but if none succeed, report only the severe errors, and if none of those, then report all the soft errors.
optional indicates whether the parser succeeded through the Maybe type.
'exactly n p' parses a precise number of items, n, using the parser p, in sequence.
'many p' parses a list of elements with individual parser p. Cannot fail, since an empty list is a valid return value.
Parse a list of items separated by discarded junk.
Parse a non-empty list of items separated by discarded junk.
Parse a list of items, discarding the start, end, and separator items.
Parse a bracketed item, discarding the brackets.
'manyFinally e t' parses a possibly-empty sequence of e's, terminated by a t. Any parse failures could be due either to a badly-formed terminator or a badly-formed element, so raise both possible errors.
Push some tokens back onto the front of the input stream and reparse. This is useful e.g. for recursively expanding macros. When the user-parser recognises a macro use, it can lookup the macro expansion from the parse state, lex it, and then stuff the lexed expansion back down into the parser.