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This file is part of Logtalk https://logtalk.org/
Copyright 1998-2018 Paulo Moura pmoura@logtalk.org

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.


This directory contains sample scripts for selected backend Prolog compilers for embedding Logtalk and Logtalk applications. See the SCRIPT.txt file for usage examples.

These scripts allow pre-compilation of the Logtalk compiler/runtime and optionally of a Logtalk application. This is a common requirement for embedding, specially when deploying applications in read-only file systems. These sample scripts should be regarded as starting points as actual use requires customization (e.g. the starting goal, inclusion of a top-level interpreter, etc). The scripts also accept command-lines options for specifying a paths files and a settings file. See the settings-embedding-sample.lgt file for settings suggestions for embedding applications.

An alternative, available in some backend Prolog compilers such as SICStus Prolog, SWI-Prolog, and YAP, is to create a saved state after loading Logtalk and a Logtalk application (or the generated Prolog code for Logtalk and a Logtalk application). Saved states are usually executables that embed both a Prolog runtime and application code. See the SCRIPT.txt file for some examples. For details on creating and using saved states, see your backend Prolog compiler documentation.

In both solutions, the reload flag should usually be set to skip (in the used settings file) to prevent reloading of already loaded code when running the embedded application or saved state. You may also want to turn off the source_data flag to reduce the size of your application.

To avoid dependencies on the Logtalk LOGTALKHOME and LOGTALKUSER environment variables, the sample scripts allow expansion of library aliases paths in the paths and settings files. If for some reason this option is not desirable, the embedded application or saved state should be run in a process that sets (possibly just for itself) the LOGTALKHOME and LOGTALKUSER environment variables to the values used during the pre-compilation of the Logtalk resources. For example, in a POSIX system, you can use something like:

$ LOGTALKHOME=/usr/local/share/logtalk LOGTALKUSER=/home/user/logtalk ./saved_state