%% Copyright (c) 1995,1996 by the University of Pennsylvania		%%

%% For information about the distributaion, copying, and modification	%%
%% of this software, please read the file COPYING located in the root	%%
%% directory of this distribnutaion. If you did not receive the file	%%
%% COPYING write to Philip Wickline at the address below.		%%

%% This program 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 file	%%
%% COPYING for more details.						%%

%% For information about the structure of the Terzo lambdaProlog	%%
%% implementation, see the file src/README in this distribution. Please	%%
%% address any questions about this code or the Terzo lambdaProlog	%%
%% implementation to Philip Wickline at <philipw@saul.cis.upenn.edu>.	%%

%% Author:								%%
%%	Philip Wickline <philipw@saul.cis.upenn.edu>			%%

module String.
import Exception, List.

	type	index_out_of_bounds, not_chr	exn.

	%	String concatenation.
	type	^				string -> string -> string.
	infixl	^				6.

	%	Returns the length of its string argument. "" has length 0.
	type	size				string -> int.

	%	chr i - Returns as a signleton string the ascii character
	% 	whose value is i. Raises not_chr if i > 255
	type	chr				int -> string.

	%	ord s - Returns the ascii value of the first character in s.
	%	Raises index_out_of_bounds if s is "". 
	type	ord				string -> int.

	%	substring s i j - returns the string starting at position i
	%	(zero indexed) in the string, and ends at position i + j.
	%	Raises index_out_of_bounds if i < 0, or i + j > size s.
	type	substring			string -> int -> int -> string.

	%	lexicographic predicates on strings:
	type	s>, s<, s>=, s=<		string -> string -> o.
	infix	s>, s<, s>=, s=<		4.