Symparsec.Parsers

Re-exported type-level symbol parsers.

You may ignore the equations that Haddock displays: they are internal and irrelevant to library usage.

Binary combinators

Parsers that combine two parsers. Any parsers that have term-level parallels will use the same fixity e.g. :<*>: is infixl 4, same as <*>.

type family pl :<*>: pr where ... infixl 4

Sequence two parsers, running left then right, and return both results.

Equations

'(plCh, plEnd, sl) :<*>: '(prCh, prEnd, sr) = '(ThenChSym plCh prCh sr, ThenEndSym prEnd, Left sl)

type family pl :*>: pr where ... infixl 4

Sequence two parsers, running left then right, and discard the return value of the left parser.

Equations

'(plCh, plEnd, sl) :*>: '(prCh, prEnd, sr) = '(ThenVLChSym plCh prCh sr, ThenVLEndSym prEnd, Left sl)

type family pl :<*: pr where ... infixl 4

Sequence two parsers, running left then right, and discard the return value of the right parser.

Consider using :*>: instead, which is simpler and potentially faster since we parse left-to-right.

Equations

'(plCh, plEnd, sl) :<*: '(prCh, prEnd, sr) = '(ThenVRChSym plCh prCh sr, ThenVREndSym prEnd, Left sl)

type family pl :<|>: pr where ... infixl 3

Parser choice. Try left; if it fails, backtrack and try right.

Be warned that this parser is experimental, and likely brittle. If possible, consider designing your schema to permit non-backtracking parsing. Or if not, have both sides always parse the same length, in which case this parser should probably work fine.

Equations

'(plCh, plEnd, sl) :<|>: '(prCh, prEnd, sr) = '(OrChSym plCh prCh sr, OrEndSym plEnd prCh prEnd sr, Left '(sl, '[]))

Positional

Parsers that relate to symbol position e.g. length, end of symbol.

type family Take n where ...

Return the next n characters.

Equations

Take 0 = '(FailChSym "Take" (ErrParserLimitation "can't take 0"), TakeEndSym, '(0, '[]))

Take n = '(TakeChSym, TakeEndSym, '(n, '[]))

type family Skip n where ...

Skip forward n characters. Fails if fewer than n characters are available.

Equations

Skip 0 = '(FailChSym "Skip" (ErrParserLimitation "can't drop 0"), SkipEndSym, 0)

Skip n = Skip' n

type End = '(FailChSym "End" (Text "expected end of symbol"), EmitEndSym, '())

Assert end of symbol, or fail.

type family Isolate n p where ...

Run the given parser isolated to the next n characters.

All isolated characters must be consumed.

Equations

Isolate 0 '(pCh, pEnd, s) = '(FailChSym "Isolate" (ErrParserLimitation "cannot isolate 0"), IsolateEndSym, '(0, s))

Isolate n '(pCh, pEnd, s) = '(IsolateChSym pCh pEnd, IsolateEndSym, '(n - 1, s))

Basic

Simple non-combinator parsers. Probably fundamental in some way e.g. very general or common.

type Literal sym = Literal' (UnconsSymbol sym)

Parse the given Symbol.

Naturals

type NatDec = NatBase 10 ParseDecimalDigitSym

Parse a decimal (base 10) natural.

type NatHex = NatBase 16 ParseHexDigitSym

Parse a hexadecimal (base 16) natural. Permits mixed-case (0-9A-Fa-f).

type NatBin = NatBase 2 ParseBinaryDigitSym

Parse a binary (base 2) natural.

type NatOct = NatBase 8 ParseOctalDigitSym

Parse an octal (base 8) natural.

type NatBase base parseDigit = '(NatBaseChSym base parseDigit, EmitEndSym, 0)

Parse a natural in the given base, using the given digit parser.