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Bluespec Compiler

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Compiler, simulator, and tools for the Bluespec Hardware Description Language. Bluespec is a single language for digital electronic hardware designs that comes in two syntactic flavors, which are interchangeable:

  • Bluespec SystemVerilog (BSV)
  • Bluespec Haskell (BH, or "Bluespec Classic")

Bluespec is a high-level hardware description language. It has a variety of advanced features including a powerful type system that can prevent errors prior to synthesis time, and its most distinguishing feature, Guarded Atomic Actions, allow you to define hardware components in a modular manner based on their invariants, and let the compiler pick a scheduler.

The toolchain was under development by Bluespec Inc for almost 20 years, and has been proven repeatedly in production designs like Flute, Piccolo, and Shakti.

The Bluespec compiler bsc emits standard Verilog for maximum compatibility with any synthesis toolchain and comes with an included simulator ("bluesim"), standard library, and TCL scripting support ("bluetcl").

The repository is still evolving. We welcome your feedback, issue reports, and pull requests.

A separate repository, bsc-contrib, exists for sharing libraries and utilities that don't (or don't yet) belong in the core tools.

A graphical environment for using BSC is available in a separate bdw repository. BDW (the BSC Development Workstation) provides a number of tools, including the ability to view simulation waveforms as source-level values.


To receive announcements about BSC and related projects, subscribe to

For questions and discussion about BSC source, subscribe to the developers' mailing list

For any questions or discussion about Bluespec HDLs, using BSC, or related projects, subscribe to

IRC users might try joining the #bluespec channel on Libera.Chat.

There's also a bluespec tag on StackOverflow.

And we've enabled the Discussions tab in this GitHub repo. This is a new feature to support discussion within the project itself. Feel free to give it a try and see if it can be useful to our community.


For the following systems, the Bluespec toolchain is available as a package that can be installed with the standard package manager:

If a package exists for your system, we recommend installing that. Otherwise, a tar-archive may be available for download from our Releases page. Install instructions can be found inside the tar-file.

If a pre-built tar-file does not exist for your system, you will need to compile BSC from source.


More details on using BSC, Bluesim, and Bluetcl can be found in the BSC User Guide.

The standard libraries that come with BSC are documented in the BSC Libraries Reference Guide.

The sources for both of these documents are found in the doc directory of this repo. Pre-built PDF files can be downloaded from the Releases page.

Language documentation, training, and tutorials can be found in the BSVlang repository.


The Bluespec toolchain is provided by Bluespec Inc and available under the BSD-3-Clause license. The source code also includes several other components under various license agreements (all of it open/copyleft software). See COPYING for copyright and license details.