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This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2023 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

To load this example and for sample queries, please see the SCRIPT.txt file.

This is a very simple example of using the new, experimental encoding/1 directive, which is fully based on the directive with the same name found on recent development releases of SWI-Prolog and YAP. Currently, this example requires Logtalk to be run with the latest versions of the CxProlog, JIProlog, XVM, SICStus Prolog, SWI-Prolog, Tau Prolog, Trealla Prolog, or YAP backends.

The following encodings are used in the source file:

• mahjong.lgt - UTF-16 full (with a BOM)
• asian.lgt - UTF-16 (with a BOM)
• babel.lgt - UTF-8 (with a BOM)
• latin.lgt - ISO-8859-1 (Latin 1)
• mythology.lgt - UTF-32 (with a BOM) The mahjong.lgt source file requires full and up-to-date UTF-16 support as it uses characters that are represented using surrogate pairs. Only XVM provides the required support. Although CxProlog and SICStus Prolog claim to support UTF-16, that support is outdated and don't include recently added code points, notably that require surrogates.

  As of the release date of this Logtalk version, only XVM, SICStus Prolog, and CxProlog support UTF-32 encodings. Attempting to compile the mythology.lgt source file with either YAP or SWI-Prolog results in a misleading syntax error.

  JIProlog, Tau Prolog, and Trealla Prolog encoding is UTF-8. Therefore, only the babel.lgt file can be used with these backends.

  Be sure to use a text editor that supports these encodings when opening these files. In addition, you may need to configure your text editor to open the source file using the declared encoding. Be sure to use a font that supports Unicode characters (both for your text editor and for the shell running your Prolog compiler interpreter).

  See the documentation of the Logtalk encoding/1 directive for its possible arguments. The Prolog and XML files generated by the Logtalk compiler use the same encoding as the compiled source files.