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Description:

ReadArgs provides the @readArgs@ IO action, which lets you tell the compiler to parse the command line arguments to fit the type signature you give. For example @(a :: Int, b :: String, c :: Float) <- readArgs@ would parse the first runtime argument as an @Int@, the second as a @String@ (no quotes required) and the third as a @Float@. If the runtime arguments are incompatible with the type signature, then a simple usage statement is given of the types needed. Continuing the previous example, if it was used in a program named @Example@, the error message for the above action would be: @ usage: Example Int String Float @ Any type that has both @Typeable@ and @Read@ instances can be used. @Char@, @String@, and @Text@ are handled specially so that command line arguments for both do not require quotes (as their @Read@ instances do). A special instance is provided for @FilePath@ so that no constructor or quotes are required. @readArgs@ also supports optional arguments and variadic arguments. Optional arguments are specified using @Maybe@, and variadic arguments using a list. @(a :: Int, b :: Maybe String, c :: [Float]) <- readArgs@ would successfully parse any of the following sets of command line arguments: @ Example 1 Example 1 2 3 4 Example 1 foo Example 1 foo 2 3 4 @ But not @ Example Example foo Example 1.0 @ Usage statements for optional and variadic arguments use command-line parlance: @ usage: Example Int [String] [Float..] @ Note that both optional and variadic parsers are greedy by default (so @Example 1 2 3 4@ was parsed as @(1, "2", [3.0,4.0])@. They may both be made non-greedy through use of the @NonGreedy@ constructor: @ ( a :: Int , NonGreedy b :: NonGreedy Maybe String , NonGreedy c :: NonGreedy [] Float ) <- readArgs @

Homepage:

https://github.com/rampion/ReadArgs

License:

BSD

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Metadata

Description

• ReadArgs provides the @readArgs@ IO action, which lets you tell the compiler to parse the command line arguments to fit the type signature you give. For example @(a :: Int, b :: String, c :: Float) <- readArgs@ would parse the first runtime argument as an @Int@, the second as a @String@ (no quotes required) and the third as a @Float@. If the runtime arguments are incompatible with the type signature, then a simple usage statement is given of the types needed. Continuing the previous example, if it was used in a program named @Example@, the error message for the above action would be: @ usage: Example Int String Float @ Any type that has both @Typeable@ and @Read@ instances can be used. @Char@, @String@, and @Text@ are handled specially so that command line arguments for both do not require quotes (as their @Read@ instances do). A special instance is provided for @FilePath@ so that no constructor or quotes are required. @readArgs@ also supports optional arguments and variadic arguments. Optional arguments are specified using @Maybe@, and variadic arguments using a list. @(a :: Int, b :: Maybe String, c :: [Float]) <- readArgs@ would successfully parse any of the following sets of command line arguments: @ Example 1 Example 1 2 3 4 Example 1 foo Example 1 foo 2 3 4 @ But not @ Example Example foo Example 1.0 @ Usage statements for optional and variadic arguments use command-line parlance: @ usage: Example Int [String] [Float..] @ Note that both optional and variadic parsers are greedy by default (so @Example 1 2 3 4@ was parsed as @(1, "2", [3.0,4.0])@. They may both be made non-greedy through use of the @NonGreedy@ constructor: @ ( a :: Int , NonGreedy b :: NonGreedy Maybe String , NonGreedy c :: NonGreedy [] Float ) <- readArgs @

Maintainers

• Gentoo Haskell (haskell@gentoo.org) - Type: project

<pkgmetadata>
	<maintainer type="project">
		<email>haskell@gentoo.org</email>
		<name>Gentoo Haskell</name>
	</maintainer>
	<longdescription>
		ReadArgs provides the @readArgs@ IO action, which lets you tell the compiler
		to parse the command line arguments to fit the type signature you give.
		
		For example @(a :: Int, b :: String, c :: Float) &lt;- readArgs@ would
		parse the first runtime argument as an @Int@, the second as a @String@ (no
		quotes required) and the third as a @Float@.
		
		If the runtime arguments are incompatible with the type signature,
		then a simple usage statement is given of the types needed.
		
		Continuing the previous example, if it was used in a
		program named @Example@, the error message for the above
		action would be:
		
		@
		usage: Example Int String Float
		@
		
		Any type that has both @Typeable@ and @Read@ instances
		can be used. @Char@, @String@, and @Text@ are handled specially so that
		command line arguments for both do not require quotes (as their
		@Read@ instances do). A special instance is provided for @FilePath@ so
		that no constructor or quotes are required.
		
		@readArgs@ also supports optional arguments and variadic arguments.
		Optional arguments are specified using @Maybe@, and variadic arguments
		using a list.  @(a :: Int, b :: Maybe String, c :: [Float]) &lt;- readArgs@
		would successfully parse any of the following sets of command line arguments:
		
		@
		Example 1
		Example 1 2 3 4
		Example 1 foo
		Example 1 foo 2 3 4
		@
		
		But not
		
		@
		Example
		Example foo
		Example 1.0
		@
		
		Usage statements for optional and variadic arguments use command-line
		parlance:
		
		@
		usage: Example Int [String] [Float..]
		@
		
		Note that both optional and variadic parsers are greedy by default
		(so @Example 1 2 3 4@ was parsed as @(1, "2", [3.0,4.0])@.  They
		may both be made non-greedy through use of the @NonGreedy@ constructor:
		
		@
		( a :: Int
		, NonGreedy b :: NonGreedy Maybe String
		, NonGreedy c :: NonGreedy [] Float
		) &lt;- readArgs
		@
	</longdescription>
</pkgmetadata>

Lint Warnings

• [Warning] Missing md5-cache for version 1.2.3. Run 'ebuild <ebuild_file> manifest' or 'egencache' to generate it.

Manifest