#--
#     This file is part of the Prelude library that provides tools to
#     enable Haskell style functional programming in Ruby.
#
#     http://prelude.rubyforge.org 
#     
#     Copyright (C) 2006 APP Design, Inc.
#
#     This library is free software; you can redistribute it and/or
#     modify it under the terms of the GNU Lesser General Public
#     License as published by the Free Software Foundation; either
#     version 2.1 of the License, or (at your option) any later version.
#
#     This library is distributed in the hope that it will be useful,
#     but WITHOUT ANY WARRANTY; without even the implied warranty of
#     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
#     Lesser General Public License for more details.
#
#     You should have received a copy of the GNU Lesser General Public
#     License along with this library; if not, write to the Free Software
#     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
#++
#
# $Id: prelude.rb 34 2007-10-23 21:38:09Z prelude $

$:.unshift(File.dirname(__FILE__))

require 'prelude/util'
require 'prelude/array_list'

# WARNING: Somehow rdoc breaks on multiline constants and does not
# generate a full list of constants below. Please see the sources for
# all defined functions and functors, there are plenty and they are all
# defined as constants.
#
# The implementation of frequently used functors is based on the code
# from Ben Yu's rparsec library, see http://rubyforge.org/frs/?group_id=2326
module Prelude

  VERSION = '0.0.5'
  
  LIST_IMPLEMENTATION = Prelude::ArrayList

  # Thrown if an illegal operation is performed on an empty list.
  class EmptyListError < RuntimeError; end

  # Thrown if a needed method is not available
  class MissingMethodError < RuntimeError; end

  # Thrown if no function was supplied
  class MissingFunctionError < RuntimeError; end

  # Thrown if something wrong with the functions' arguments
  class ArgumentError < RuntimeError; end

  # Thrown if bad list is encountered
  class ImproperListError < RuntimeError; end

  # A helper method to create an empty list of a given list type. Has to be a proper list.
  def Prelude.new_list(list=nil)
    res = LIST_IMPLEMENTATION.new(list)
    #p "new_list #{res.inspect}"
    raise ImproperListError unless res.kind_of?(Prelude::ProperList)
    res
  end

  # A helper method to generate a new lambda that uses native implementation if available
  def Prelude.use_native(meth)
    list = Prelude.new_list
    if list.kind_of?(Prelude::ProperList) and list.respond_to?(meth)
      Lambda.new { |l, *args| l.method(meth)[*args] }
    else
      nil
    end
  end

end # Prelude

require 'prelude/lambda'
require 'prelude/functors'
require 'prelude/functions'
require 'prelude/monad'