ArgParse.idr

-- ------------------------------------------------------------ [ ArgParse.idr ]
-- Description :
-- Copyright   : (c) Jan de Muijnck-Hughes
-- License     : see LICENSE
-- --------------------------------------------------------------------- [ EOH ]
module ArgParse

import public ArgParse.Model

import ArgParse.Parser
import public ArgParse.Error

%access export
%default total
-- ----------------------------------------------------------------- [ Records ]

private
convOpts : (Arg -> a -> Maybe a)
        -> a
        -> List Arg
        -> Either ArgParseError a
convOpts  _   o Nil       = pure o
convOpts conv o (x :: xs) = case conv x o of
    Nothing => Left (InvalidOption x)
    Just o' => do
      os <- convOpts conv o' xs
      pure os

||| Parse arguments using a record.
|||
||| @orig The starting value of the record representing the options.
||| @conv A user supplied conversion function used to update the record.
||| @args The *unmodified* result of calling `System.getArgs` or `Effects.System.geArgs`.
parseArgs : (orig : a)
        -> (conv : Arg -> a -> Maybe a)
        -> (args : List String)
        -> Either ArgParseError a
parseArgs o _    Nil     = pure o
parseArgs o _    [a]     = pure o
parseArgs o func (a::as) = do
    case parseArgs (unwords as) of
      Left err  => Left (ParseError err)
      Right res => do
        r <- convOpts func o res
        pure r

-- --------------------------------------------------------------------- [ EOF ]