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Project: CλaSH
Description: Functional hardware description language
CλaSH Liaison: Richard Tobias

What is CλaSH

CλaSH (pronounced ‘clash’) is a functional hardware description language that borrows both its syntax and semantics from the functional programming language Haskell. It provides a familiar structural design approach to both combinational and synchronous sequential circuits. The CλaSH compiler transforms these high-level descriptions to low-level synthesizable VHDL, Verilog, or SystemVerilog.

Features of CλaSH:

  • Strongly typed, but with a very high degree of type inference, enabling both safe and fast prototyping using concise descriptions.
  • Interactive REPL: load your designs in an interpreter and easily test all your component without needing to setup a test bench.
  • Compile your designs for fast simulation.
  • Higher-order functions, in combination with type inference, result in designs that are fully parametric by default.
  • Synchronous sequential circuit design based on streams of values, called Signals, lead to natural descriptions of feedback loops.
  • Multiple clock domains, with type safe clock domain crossing.
  • Template language for introducing new VHDL/(System)Verilog primitives.

From the CλaSH website

CλaSH Project Ideas

Christiaan Baaij, one of the principle creators of CλaSH gave these ideas for hackathon projects:

A project that I'm think about is:

  • To get a decent build system for CλaSH that includes regression testing with a verilog simulator and calling the appropriate EDA tools from either Altera or Xilinx to synthesize, place and route and then download the bitfile to the FPGA itself. A good starting point for this is the build system that Austin Seipp created in his claap project. You can find this build system inside of his project at

Good FPGA Boards to Bring to BayHac2017 CλaSH Hackathon

I will bring a few DE0-nano boards to the hackathon. They are quite inexpensive and can be purchased for about $85 on DigiKey, adafruit and other locations on the web.

A good list of boards can be found here:

The list is copied here (thanks goes to darchon on the subreddit for haskell):