libghc-readargs-doc 1.2.1-2build1 / usr / share / doc / libghc-readargs-doc / html / ReadArgs.txt

-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Simple command line argument parsing
--   
--   ReadArgs provides the <tt>readArgs</tt> IO action, which lets you tell
--   the compiler to parse the command line arguments to fit the type
--   signature you give.
--   
--   For example <tt>(a :: Int, b :: String, c :: Float) &lt;-
--   readArgs</tt> would parse the first runtime argument as an
--   <tt>Int</tt>, the second as a <tt>String</tt> (no quotes required) and
--   the third as a <tt>Float</tt>.
--   
--   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
--   <tt>Example</tt>, the error message for the above action would be:
--   
--   <pre>
--   usage: Example Int String Float
--   </pre>
--   
--   Any type that has both <tt>Typeable</tt> and <tt>Read</tt> instances
--   can be used. <tt>Char</tt>, <tt>String</tt>, and <tt>Text</tt> are
--   handled specially so that command line arguments for both do not
--   require quotes (as their <tt>Read</tt> instances do). A special
--   instance is provided for <tt>FilePath</tt> so that no constructor or
--   quotes are required.
--   
--   <tt>readArgs</tt> also supports optional arguments and variadic
--   arguments. Optional arguments are specified using <tt>Maybe</tt>, and
--   variadic arguments using a list. <tt>(a :: Int, b :: Maybe String, c
--   :: [Float]) &lt;- readArgs</tt> would successfully parse any of the
--   following sets of command line arguments:
--   
--   <pre>
--   Example 1
--   Example 1 2 3 4
--   Example 1 foo
--   Example 1 foo 2 3 4
--   </pre>
--   
--   But not
--   
--   <pre>
--   Example
--   Example foo
--   Example 1.0
--   </pre>
--   
--   Usage statements for optional and variadic arguments use command-line
--   parlance:
--   
--   <pre>
--   usage: Example Int [String] [Float..]
--   </pre>
--   
--   Note that both optional and variadic parsers are greedy by default (so
--   <tt>Example 1 2 3 4</tt> was parsed as <tt>(1, <a>2</a>,
--   [3.0,4.0])</tt>. They may both be made non-greedy through use of the
--   <tt>NonGreedy</tt> constructor:
--   
--   <pre>
--   ( a :: Int
--   , NonGreedy b :: NonGreedy Maybe String
--   , NonGreedy c :: NonGreedy [] Float
--   ) &lt;- readArgs
--   </pre>
@package ReadArgs
@version 1.2.1

module ReadArgs

-- | parse the desired argument tuple from the command line or print a
--   simple usage statment and quit
readArgs :: ArgumentTuple a => IO a

-- | read args from the given strings or print a simple usage statment and
--   quit (so you can do option parsing first)
readArgsFrom :: ArgumentTuple a => [String] -> IO a

-- | a class for types that can be parsed from exactly one command line
--   argument
class Arguable a
parse :: Arguable a => String -> Maybe a
name :: Arguable a => a -> String

-- | a class for types that can be parsed from some number of command line
--   arguments
class Argument a
parseArg :: Argument a => [String] -> [(a, [String])]
argName :: Argument a => a -> String

-- | a wrapper type to indicate a non-greedy list or maybe
newtype NonGreedy m a
NonGreedy :: m a -> NonGreedy m a
unNonGreedy :: NonGreedy m a -> m a

-- | a class for tuples of types that can be parsed from the entire list of
--   arguments
class ArgumentTuple a
parseArgsFrom :: ArgumentTuple a => [String] -> Maybe a
usageFor :: ArgumentTuple a => a -> String

-- | use :&amp; to construct arbitrary length tuples of any parsable
--   arguments
data (:&) a b
(:&) :: a -> b -> :& a b
instance [overlap ok] Show (m a) => Show (NonGreedy m a)
instance [overlap ok] Eq (m a) => Eq (NonGreedy m a)
instance [overlap ok] (Show a, Show b) => Show (a :& b)
instance [overlap ok] (Eq a, Eq b) => Eq (a :& b)
instance [overlap ok] (Argument o, Argument n, Argument m, Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (o, n, m, l, k, j, i, h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument n, Argument m, Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (n, m, l, k, j, i, h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument m, Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (m, l, k, j, i, h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument l, Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (l, k, j, i, h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument k, Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (k, j, i, h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument j, Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (j, i, h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument i, Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (i, h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument h, Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (h, g, f, e, d, c, b, a)
instance [overlap ok] (Argument g, Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (g, f, e, d, c, b, a)
instance [overlap ok] (Argument f, Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (f, e, d, c, b, a)
instance [overlap ok] (Argument e, Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (e, d, c, b, a)
instance [overlap ok] (Argument d, Argument c, Argument b, Argument a) => ArgumentTuple (d, c, b, a)
instance [overlap ok] (Argument c, Argument b, Argument a) => ArgumentTuple (c, b, a)
instance [overlap ok] (Argument b, Argument a) => ArgumentTuple (b, a)
instance [overlap ok] Argument a => ArgumentTuple a
instance [overlap ok] (Argument a, ArgumentTuple y) => ArgumentTuple (a :& y)
instance [overlap ok] ArgumentTuple ()
instance [overlap ok] Argument String
instance [overlap ok] Argument (m a) => Argument (NonGreedy m a)
instance [overlap ok] Arguable a => Argument [a]
instance [overlap ok] Arguable a => Argument (Maybe a)
instance [overlap ok] Arguable a => Argument a
instance [overlap ok] Arguable Char
instance [overlap ok] Arguable FilePath
instance [overlap ok] Arguable Text
instance [overlap ok] Arguable String
instance [overlap ok] (Typeable t, Read t) => Arguable t