Tools for building compilers in F#

This repository contains a collection of tools which assist in implementing compilers, interpreters, and other language-based tools in F#.

The Facio library can be installed from NuGet:
PM> Install-Package Facio -Pre


FSharpLex is a tool for generating lexical analyzers ("tokenizers") from a lexer specification file (*.fsl).

The lexer specification files used by FSharpLex and the lexers it generates are largely compatible with the older fslex tool from the F# PowerPack.


FSharpYacc is a tool for generating parsers for context-free grammars (CFGs) described by a parser specification file (*.fsy).

The parser specification files used by FSharpYacc and the parsers it generates are largely compatible with the older fsyacc tool from the F# PowerPack.


Graham is a library for creating, manipulating, and analyzing context-free grammars (CFGs).

Graham also includes algorithms for generating parser automata, providing a flexible, generic approach to implementing parser-generator tools like FSharpYacc.


Example projects built on top of Facio compiler tools you can find in separate Facio-Examples GitHub repository.

Implementation Status

These tools are still in development and should be considered alpha-quality.

The core functionality has been implemented and passes some simple tests. The FSharpLex and FSharpYacc tools are able to bootstrap themselves, but there is still much work to be done for the user-facing parts of the code.

At this time, FSharpLex and FSharpYacc generate code which uses the lexer/parser table interpreters for fslex and fsyacc (originally provided as part of the F# PowerPack). I've copied the code for these interpreters from the F# PowerPack repository into the LegacyInterpreters project in this repository for convenience; this also allows you to build the interpreters for newer versions of .NET (the F# PowerPack was originally designed for .NET 2.0).


All projects in this repository are licensed under the terms of the Apache 2.0 license.

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