System.Console.MultiArg.Error

Errors. Parsing a command line when a user has entered it correctly is easy; doing something sensible when an incorrect line has been entered is a bit more difficult. This module exports an Error typeclass, which you can declare instances of in order to have your own type to represent errors. Or you can use SimpleError, which is already an instance of Error.

Documentation

class Error e where

Instances of this typeclass represent multiarg errors. You can declare instances of this typeclass so that you can use your own type for errors. This makes multiarg easy to integrate into your own programs. Then you can also easily add other errors, which you can report from the parsers you build by calling throw.

Methods

parseErr :: Expecting -> Saw -> e

Store an error in your Error instance.

Instances

Error Text

Error SimpleError

data SimpleError

A simple type that is already an instance of Error.

Constructors

SimpleError Expecting Saw

Instances

Eq SimpleError

Show SimpleError

Error SimpleError

printError :: SimpleError -> Text

Generates error messages.

data Expecting

Each error consists of two parts: what the parser was expecting to see, and what it actually saw. This type holds what the parser expected to see. If you just want to give some text to be used in an error message, use ExpTextError. To generate a generic error, use ExpOtherFailure.

Constructors

ExpPendingShortOpt ShortOpt

ExpExactLong LongOpt

ExpApproxLong (Set LongOpt)

ExpLongOptArg

ExpPendingShortArg

ExpStopper

ExpNextArg

ExpNonOptionPosArg

ExpEnd

ExpNonGNUExactLong LongOpt

ExpMatchingApproxLong LongOpt (Set LongOpt)

ExpNonGNUMatchingApproxLong LongOpt (Set LongOpt)

ExpApproxWord (Set Text)

ExpOptionOrPosArg

ExpTextError Text

ExpNonPendingShortOpt ShortOpt

ExpNotFollowedBy

ExpOtherFailure

Instances

Eq Expecting

Show Expecting

printExpecting :: Expecting -> Text

Generates an error message from an Expecting.

data Saw

What the parser actually saw. To give some text to be used in the error message, use SawTextError. To generate a generic error, use SawOtherFailure.

Constructors

SawNoPendingShorts

SawWrongPendingShort Char

SawNoArgsLeft

SawEmptyArg

SawSingleDashArg

SawStillPendingShorts TextNonEmpty

SawNotShortArg Text

SawWrongShortArg Char

SawNotLongArg Text

SawWrongLongArg Text

SawNoMatches Text

SawMultipleMatches (Set LongOpt) Text

SawNoPendingShortArg

SawAlreadyStopper

SawNewStopper

SawNotStopper

SawLeadingDashArg Text

SawMoreInput

SawGNULongOptArg Text

SawNotMatchingApproxLong Text LongOpt

SawMatchingApproxLongWithArg Text

SawMultipleApproxMatches (Set Text) Text

SawNoOption

SawNoOptionOrPosArg

SawTextError Text

SawFollowedBy

SawOtherFailure

Instances

Eq Saw

Show Saw

printSaw :: Saw -> Text

Generates error messages from a Saw.