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GHC 9.10.3 · lts/ghc-9.10.x · 248f8f0 · 2026-10-05

Modulehspec-attoparsec-0.1.0.2Haskell2010

Test.Hspec.Attoparsec

Utility functions for testing attoparsec parsers, each one providing an example of how to use it.

  • 2 classes
  • 5 values

Equality-based combinator

1 declaration
valueshouldParse :: (Eq a, Show a) => Either String a -> a -> Expectation
#

Create an expectation by saying what the result should be. Intended to be used with ~> as follows:

  "<!-- foo -->" ~> htmlCommentParser
    `shouldParse` TagComment " foo "

Predicate-based combinator

1 declaration
valueparseSatisfies :: Show a => Either String a -> (a -> Bool) -> Expectation
#

Create an expectation by saying that the parser should successfully parse a value and that this value should satisfy some predicate.

This can fail if the parsing doesn't succeed or if it succeeds but the value doesn't match the predicate.

">>>" ~> many (char '>')
  `parseSatisfies` ((==3) . length)

Inspecting the result

2 declarations

Inspecting unconsumed input

1 declaration
valueleavesUnconsumed
  1. :: (Source p s s' r, Leftover r s)
  2. => r a
  3. -> s
  4. -> Expectation
#

Checking that the given parser succeeds and yields the given part of the input unconsumed. Intended to be used in conjunction with ~?>

("xa" :: Text) ~?> char 'x'
  `leavesUnconsumed` "a"

The Source class, connecting parsers and inputs

1 declaration
classclass (Eq string, Show string, IsString string) => Source (parser :: Type -> Type -> Type) string string' (result :: Type -> Type) | string -> parser, string -> result, string -> string' where
#

A class where each instance will just teach how to get an Either or the specific result type associated to the parser for the given input type.

Methods

  • (~>) :: string -> parser string' a -> Either String a

    Feed some input to a parser and extract the result as either a failure String or an actually parsed value. Can be read as fed to.

    -- "<a ...>" fed to an HTML parser 
    "<a href=\"/foo\">Go to foo</a>" ~> htmlParser :: Either String a
  • (~?>) :: string -> parser string' a -> result a

    Feed some input to a parser and extract it as the appropriate result type from that module.

    This is not currently useful in the library per se, but is used in test-suites directly where we generally only deal with one concrete set of parser, input and result types. This lets us inspect the result in any way we want, e.g in conjunction with shouldSatisfy or a custom hspec combinator.

Instances4Source

The Leftover class, letting us inspect unconsumed input

1 declaration
classclass Leftover (r :: Type -> Type) s | r -> s where
#

Class for generically inspecting unconsumed input

Methods

  • leftover :: r a -> Maybe s

    Get the unconsumed input from the result of a parser

    Returns Nothing if the unconsumed input is ""

Instances4Leftover