ErrorMethods
This class exposes helpful combinators that are specialised for generating more helpful errors messages. For a description of why the library is designed in this way, see: the Parsley wiki
This class exposes helpful combinators that are specialised for generating more helpful errors messages. For a description of why the library is designed in this way, see: the Parsley wiki
- Value Params
- con
A conversion (if required) to turn
pinto a parser- p
The parser which serves as the method receiver
- Version
3.0.0
Value members
Concrete methods
Same as fail, except allows for a message generated from the result of the failed parser. In essence, this
is equivalent to p >>= (x => fail(msggen(x)) but requires no expensive computations from the use of >>=.
Same as fail, except allows for a message generated from the result of the failed parser. In essence, this
is equivalent to p >>= (x => fail(msggen(x)) but requires no expensive computations from the use of >>=.
- Value Params
- msggen
The generator function for error message, creating a message based on the result of invokee
- Returns
A parser that fails if it succeeds, with the given generator used to produce the error message
Attempts to first filter the parser to ensure that pf is defined over it. If it is, then the function pf
is mapped over its result. Roughly the same as a guard then a map.
Attempts to first filter the parser to ensure that pf is defined over it. If it is, then the function pf
is mapped over its result. Roughly the same as a guard then a map.
- Value Params
- msg
The message used for the error if the input failed the check
- pf
The partial function
- Returns
The result of applying
pfto this parsers value (if possible), or fails- Since
3.0.0
Attempts to first filter the parser to ensure that pf is defined over it. If it is, then the function pf
is mapped over its result. Roughly the same as a guard then a map.
Attempts to first filter the parser to ensure that pf is defined over it. If it is, then the function pf
is mapped over its result. Roughly the same as a guard then a map.
- Value Params
- msggen
Generator function for error message, generating a message based on the result of the parser
- pf
The partial function
- Returns
The result of applying
pfto this parsers value (if possible), or fails- Since
3.0.0
Similar to label, except instead of providing an expected message replacing the original tag, this combinator
adds a ''reason'' that the error occurred. This is in complement to the label. The reason is only added when
the parser fails, and will disappear if any further progress in the parser is made (unlike labels, which may
reappear as "hints").
Similar to label, except instead of providing an expected message replacing the original tag, this combinator
adds a ''reason'' that the error occurred. This is in complement to the label. The reason is only added when
the parser fails, and will disappear if any further progress in the parser is made (unlike labels, which may
reappear as "hints").
- Value Params
- reason
The reason why a parser failed
- Since
3.0.0
Filter the value of a parser; if the value returned by the parser is defined for the given partial function, then
the filterOut fails, using the result of the function as the ''reason'' (see explain), otherwise the parser
succeeds
Filter the value of a parser; if the value returned by the parser is defined for the given partial function, then
the filterOut fails, using the result of the function as the ''reason'' (see explain), otherwise the parser
succeeds
- Value Params
- pred
The predicate that is tested against the parser result
- Returns
The result of the invokee if the value failed the predicate
- Since
3.0.0
Similar to filterOut, except the error message generated yields a ''true failure''. This means that it will
uses the same mechanism as fail, as opposed to the reason provided by filterOut
Similar to filterOut, except the error message generated yields a ''true failure''. This means that it will
uses the same mechanism as fail, as opposed to the reason provided by filterOut
- Value Params
- pred
The predicate that is tested against the parser result and produces error messages
- Returns
The result of the invokee if it fails the predicate
- Since
2.8.0
Hides the "expected" error message for a parser.
Hides the "expected" error message for a parser.
- Since
3.0.0
Sets the expected message for a parser. If the parser fails then expected msg will added to the error.
The label is only applied if the error message does not observe any consumption of input.
Sets the expected message for a parser. If the parser fails then expected msg will added to the error.
The label is only applied if the error message does not observe any consumption of input.
- Since
3.0.0
Same as unexpected, except allows for a message generated from the result of the failed parser. In essence,
this is equivalent to p >>= (x => unexpected(x)) but requires no expensive computations from the use of
>>=
Same as unexpected, except allows for a message generated from the result of the failed parser. In essence,
this is equivalent to p >>= (x => unexpected(x)) but requires no expensive computations from the use of
>>=
- Value Params
- msggen
The generator function for error message, creating a message based on the result of invokee
- Returns
A parser that fails if it succeeds, with the given generator used to produce an unexpected message