Safe Haskell	Safe
Language	Haskell2010

Text.LambdaOptions.Parseable

Description

Class used for parsing command-line options.

Synopsis

class Parseable a where
- parse :: [String] -> (Maybe a, Int)
simpleParse :: (String -> Maybe a) -> [String] -> (Maybe a, Int)
repeatedParse :: Parseable a => Int -> [String] -> (Maybe [a], Int)

Documentation

class Parseable a where Source #

Class describing parseable values. Much like the Read class.

Methods

parse :: [String] -> (Maybe a, Int) Source #

Given a sequence of strings, parse returns Nothing and the number of strings consumed if the parse failed. Otherwise, parse returns Just the parsed value and the number of strings consumed.

Element-wise, an entire string must be parsed in the sequence to be considered a successful parse.

Instances

Parseable Char Source #	Parses a single character string.
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe Char, Int) Source #
Parseable Float Source #	Parses a `Float` using its `Read` instance.
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe Float, Int) Source #
Parseable Int Source #	Parses an `Int` using its `ReadBounded` instance.
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe Int, Int) Source #
Parseable Integer Source #	Parses an `Integer` using its `Read` instance.
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe Integer, Int) Source #
Parseable Word Source #	Parses a `Word` using its `ReadBounded` instance.
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe Word, Int) Source #
Parseable () Source #	Always succeeds and never consumes any input.
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe (), Int) Source #
Parseable String Source #	Identity parser. Ex: `parse "abc" == (Just "abc", 1)`
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe String, Int) Source #
Parseable a => Parseable (Maybe a) Source #	Greedily parses a single argument or no argument. Never fails.
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe (Maybe a), Int) Source #
Parseable a => Parseable (List a) Source #	Greedily parses arguments item-wise. Never fails. Example: `parse (words "5 67 NaN") == (Just (List [5,67]), 2)`
Instance details Defined in Text.LambdaOptions.List Methods parse :: [String] -> (Maybe (List a), Int) Source #
(Parseable a, Parseable b) => Parseable (a, b) Source #
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe (a, b), Int) Source #
(Parseable a, Parseable b, Parseable c) => Parseable (a, b, c) Source #
Instance details Defined in Text.LambdaOptions.Parseable Methods parse :: [String] -> (Maybe (a, b, c), Int) Source #

simpleParse :: (String -> Maybe a) -> [String] -> (Maybe a, Int) Source #

Turns a parser of a single string into a parser suitable for a Parseable instance.

Useful for implementing a Parseable for a type with a Read instance by supplying readMaybe to this function.

Note: The string is not tokenized in any way before being passed into the input parser.

repeatedParse :: Parseable a => Int -> [String] -> (Maybe [a], Int) Source #

Repeatedly applies parse the given number of times, accumulating the results.

Useful for implementing new parsers.

Example:

data Point = Point Float Float Float

instance Parseable Point where
    parse strs = case repeatedParse 3 strs of
        (Just [x,y,z], n) -> (Just (Point x y z), n)`
        (Nothing, n) -> (Nothing, n)