Fable README

fble-0.5 (2025-07-13,fble-0.4-212-ga8f8ad0f)

Fable is a programming language project. It includes a specification, reference implementation, library, and sample applications for the fble programming language.

Overview

Start with the simplicity of C. Redesign the foundations from the ground up based on a strong type system and functional programming. Use automatic memory management and make sure there is a clear way to reason about performance. Include support for generics and modularity. Remove as many hard edges, corner cases and redundancies in the language as possible.

The result is a simple, general purpose, statically typed, strict, pure functional programming language with automatic memory management, support for polymorphism and modularity, user-defined primitive data types, and a hint of C-like syntax.

Source

The source code for fble is available from github at https://github.com/ruhler/fable.

Documentation

Fble Language Specification

spec/fble.fbld

Fble Style Guide

spec/style.fbld

Fbld Document Markup Specification

fbld/fbld.fbld

Tutorials

tutorials/Tutorials.fbld

Release Notes

Release.fbld

The latest generated documentation is also available online at https://ruhler.github.io/fable.

Directory Structure

bin/

Source code for fble compiler binaries.

book/

Drafts for a book about the design of the fble language.

fbld/

A lightweight document markup language used for documenting fble.

include/

Public header files for the fble library.

lib/

Source code for an fble interpreter and compiler implemented in C.

pkgs/

Sample fble library and application packages.

spec/

Specification of the fble language, including spec tests.

test/

Source code for fble test binaries and other test utilities.

thoughts/

A collection of running discussions about fble.

tutorials/

Fble language tutorials.

vim/

Vim syntax files for fbld and fble.

Build Requirements

To build and run the tests for all of fble, the following software is required. The version numbers provided are versions that are known to work:

Expect 5.45.4

To test fble debugging.

GNU Binutils for Debian 2.31.1

For assembling compiled fble programs.

GNU Bison 3.3.2

For generating the fble parser.

GNU Compiler Collection (Debian 8.3.0-6) 8.3.0

For compiling fble.

GNU coreutils 8.30

Used in the build system.

GNU Debugger (Debian 8.2.1-2+b3) 8.2.1

Used to test fble debugging.

GNU diffutils 3.7

For some test cases.

GNU grep 3.3

For some test cases.

GNU groff version 1.22.4

For formatting help usage text.

Ninja 1.10.1

For the build system.

Open GL 1.2

For graphical fble apps.

Simple DirectMedia Layer 2.0.9

For graphical fble apps.

Tcl 8.6

For generating build ninja files.

To install required dependencies on a debian based system:

apt install \
  expect binutils bison coreutils \
  gcc gdb diffutils grep groff-base \
  ninja-build libgl-dev libsdl2-dev tcl8.6

To install required dependencies on an MSYS2 UCRT64 based system:

 pacman -S tcl ninja gcc bison groff diffutils \
   mingw-w64-ucrt-x86_64-toolchain \
   mingw-w64-ucrt-x86_64-SDL2 \
   mingw-w64-ucrt-x86_64-mesa
 export MSYS2_ARG_CONV_EXCL='*'

Build

To build and install:

./configure --prefix=/usr/local && ninja && ninja install

Additional ninja targets:

tests

Runs tests on uninstalled binaries.

www

Builds html documentation.

check

Builds and tests everything without installing anything.

Vim Files

Vim ftplugin, syntax, and indent files for the fble language are available in the `vim/` directory. You can run the following commands to install these files:

mkdir -p ~/.vim/ftdetect ~/.vim/ftplugin ~/.vim/indent ~/.vim/syntax
cp vim/ftdetect/* ~/.vim/ftdetect
cp vim/ftplugin/* ~/.vim/ftplugin
cp vim/indent/* ~/.vim/indent
cp vim/syntax/* ~/.vim/syntax