Fun, Tiny Language

Synopsys

FTL is provided as a library which makes it simple to create shell-style utilities that expect input in the form

    command arg arg
    command arg
    command
    command arg
    :
    etc.

The user can (optionally) add a number of additional pre-defined commands that are sufficiently expressive to write programs in.

Motivation

Using the library allows the user to implement just the commands necessary without needing to implement things like:

• command line editing (depending on the build)
• concatenating lines using separated with a terminal ''
• ignoring comment lines with an initial '#'
• variable setting and expansion
• including scripts from other files

The commands implemented can be scripted using FTL to implement more complex commands in a way that is simpler than writing additional C/C++.

Also FTL, the language used to extend the scripts, is conceptually tiny and quite fun to explore.

Obtaining the code

Typically this command can be used to clone the repository into a new directory called 'FTL':

git clone https://github.com/GrayGirling/FTL.git

Building

The code is intended to be portable among at least Windows, Linux and MacOS systems.

It is built in a traditional 'make' environment. While this is trivially available in Linux and MacOS it needs a little work to establish in Windows.

A number of solutions are possible in windows:

• In Windows 10 (post the 2017 'Creators' edition) it is possible to use the Ubuntu Linux subsystem
• Cygwin can be downloaded and installed (selecting the mingw compilers), https://www.cygwin.com/
• MinGW can be used, http://www.mingw.org/
• Git for Windows can be used, https://git-scm.com/download/win

The code includes the main library - which you can use in your utility as well as:

• some extensions for additional sets of functions in subdirectory lib
• two example utilities: "ftl" - which just allows basic FTL programs to be run; and, "penv" - which provides an example tool (for maintaining "permanent" environment state)
• some examples of FTL functions that you may find useful in subdirectory flib

Documentation

You can find (web format) documentation in directory 'doc' once you have cloned this repository.

There is a description of the use of the library to create C or C++ command-line programs here.

This describes how the tool (or a new tool) can be built in different software environments (such as on Windows, MacOS or Linux).

When using FTL as the basis of a utility you may need to know what the built-in commands and functions are - see the user guide: here (or as PDF).

A simple outline of the language is contained in: spec.

License

This is the FTL library written by Gray Girling while at Solarflare Communications Inc., extended at Broadcom Inc and NXP Semiconductors Inc.

It has a BSD-style license - see the LICENSE file in this directory for most of the code.

The code also includes an optional BSD-licensed line editing library (the use of which will be controlled by your utility's Makefile).

Three options providing for line editing are available:

• no line editing (e.g. not really necessary when run from some Windows shells)
• the "standard" readline line editor, under a GPL license (which will require your program to be GPL licensed)
• the linenoise line editor, under a (non-viral) BSD license (see LICENSE-linenoise).

Testing

There is a test suite that requires the use of "bash" which tests many of the bult-in functions and can be used to spot regressions. (Currently these tests work best when not used under Windows.) Help can be found using

test/check -h