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GHC 9.14.1 · lts/ghc-9.14.x · 45dd537 · 2026-10-11

Modulestreamly-core-0.3.1Haskell2010

Streamly.Internal.Data.ParserK

  • 4 types
  • 13 values
valuechainl
  1. :: ParserK b IO a
  2. -> ParserK b IO (a -> a -> a)
  3. -> a
  4. -> ParserK b IO a
#

chainl p op x is like chainl1 but allows zero or more occurrences of p, separated by op. If there are zero occurrences of p, the value x is returned.

valuechainl1 :: ParserK b IO a -> ParserK b IO (a -> a -> a) -> ParserK b IO a
#

chainl1 p op x parses one or more occurrences of p, separated by op. Returns a value obtained by a left associative application of all functions returned by op to the values returned by p.

Example4 expressions
num = Parser.decimalplus = Parser.char '+' *> pure (+)expr = ParserK.chainl1 (StreamK.toParserK num) (StreamK.toParserK plus)StreamK.parse expr $ StreamK.fromStream $ Stream.fromList "1+2+3"Right 6

If you're building full expression parsers with operator precedence and associativity, consider using makeExprParser from the parser-combinators package.

See also deintercalate.

valuechainr
  1. :: ParserK b IO a
  2. -> ParserK b IO (a -> a -> a)
  3. -> a
  4. -> ParserK b IO a
#

chainr p op x is like chainr1 but allows zero or more occurrences of p, separated by op. If there are zero occurrences of p, the value x is returned.

valuechainr1 :: ParserK b IO a -> ParserK b IO (a -> a -> a) -> ParserK b IO a
#

Like chainl1 but parses right associative application of the operator instead of left associative.

Example4 expressions
num = Parser.decimalpow = Parser.char '^' *> pure (^)expr = ParserK.chainr1 (StreamK.toParserK num) (StreamK.toParserK pow)StreamK.parse expr $ StreamK.fromStream $ Stream.fromList "2^3^2"Right 512
valuedie :: String -> ParserK a m b
#

A parser that always fails with an error message without consuming any input.

Pre-release

valuefromPure :: b -> ParserK a m b
#

A parser that always yields a pure value without consuming any input.

Pre-release

datadata ParseResult b
#

The parser's result.

Int is the position index in the stream relative to the position on entry i.e. when the parser started running. When the parser enters the position index is zero. If the parser consumed n elements then the new position index would be n. If the parser is backtracking then the position index would be negative.

Pre-release

Constructors

Instances1Functor
newtypenewtype ParserK a (m :: Type -> Type) b
#

A continuation passing style parser representation.

Constructors

Instances7Monad, Functor, MonadFail, Applicative, Alternative, MonadPlus, …
  • Monad m => Monad (ParserK a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type

    Monad composition can be used for lookbehind parsers, we can dynamically compose new parsers based on the results of the previously parsed values.

  • Functor m => Functor (ParserK a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type

    Map a function on the result i.e. on b in Parser a m b.

  • Monad m => MonadFail (ParserK a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type
  • Monad m => Applicative (ParserK a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type

    f <$> p1 <*> p2 applies parsers p1 and p2 sequentially to an input stream. The first parser runs and processes the input, the remaining input is then passed to the second parser. If both parsers succeed, their outputs are applied to the function f. If either parser fails, the operation fails.

  • Monad m => Alternative (ParserK a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type

    p1 <|> p2 passes the input to parser p1, if it succeeds, the result is returned. However, if p1 fails, the parser driver backtracks and tries the same input on the alternative parser p2, returning the result if it succeeds.

  • Monad m => MonadPlus (ParserK a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type

    mzero is same as empty, it aborts the parser. mplus is same as <|>, it selects the first succeeding parser.

  • MonadIO m => MonadIO (ParserK a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type
datadata Step a (m :: Type -> Type) r
#

The intermediate result of running a parser step. The parser driver may (1) stop with a final result (Done) with no more inputs to be accepted, (2) generate an intermediate result (Partial) and accept more inputs, (3) generate no result but wait for more input (Continue), (4) or fail with an error (Error).

The Int is a count by which the current stream position should be adjusted before calling the next parsing step.

See the documentation of Streamly.Data.Parser.Step for more details, this has the same semantics.

Pre-release

Constructors

Instances1Functor
  • Functor m => Functor (Step a m)Defined in streamly-core-0.3.1 · Streamly.Internal.Data.ParserK.Type

Deprecated

2 declarations