CLaSH: A functional hardware description language

http://hackage.haskell.org/package/clash-prelude-0.5/docs/CLaSH-Tutorial.html

by rwosync • 12 years ago

87 44 12 years ago

hackage.haskell.org

I think we have a winner for the most poorly named programming language of the last decade. I thought that "Go" and "Hack" were bad, but at least I could type those on my keyboard.

elliotec• 12 years ago

Seriously. I spent more time trying to figure out how to read/say it than reading about it. C(lambda)aSH? clambdaash? Oh, CLaSH.

dllthomas• 12 years ago

Clam-dash. It makes your shellfish go fast, or your car smell.

Dorian-Marie• 12 years ago

The command-line tool / url / package name / ... are all "CLaSH"

Dewie• 12 years ago

I am able to get about 4 decent/good results by googling "clash language". Though I got more results with "CλaSH language".

jonemo• 12 years ago

Squirrel is also high up on that list.

cottonseed• 12 years ago

I think ClaSH is the proper romanization.

mathieuh• 12 years ago

Clash? C-lambda-ash? C-lambda-a-ess-aitch? C-lash?

ZenoArrow• 12 years ago

Interesting language, I'll be interested to see how Clash develops.

blueintegral• 12 years ago

Is this meant for hardware people or software people? Because I'm a hardware guy and I don't know Haskell. None of my EE friends know Haskell either. I really don't see a serious hardware engineer using this over VHDL or Verilog, even if it is more beautiful or provably better or whatever.

zhemao5• 12 years ago

Strangely enough, alternative HDLs embedded in Haskell seem to be a thing. Besides this, there is also Bluespec and Lava.

http://wiki.bluespec.com/

http://raintown.org/lava/

sitkack4• 12 years ago

Tom Hawkins is probably around here somewhere.

http://en.wikipedia.org/wiki/Atom_(programming_language)

marcosdumay2• 12 years ago

Immutability looks too much like hardware.

pipeep2• 12 years ago

From the limited amount of VHDL I did in my Digital Design class at my university, I found hardware description similar to functional programming. State is expensive to represent in hardware (you need latches, flip-flops, etc), and so VHDL's concept of signals is similar to constants, and components map well to pure functions. With an intelligent enough compiler, I think this is totally feasible.

From a more short-term practical standpoint, no, I don't expect anyone to use this. Hardware engineers are incredibly stubborn when it comes to software. Their work typically involves large time investments with lots of costs and risks. For better or worse, they typically don't ever want to add more risk by using an "untrusted" tool, creating a chicken-and-egg problem.

In the second paragraph, the author admits that there's not yet a good way to represent a recursive algorithm in his language. I think this is more of a proof-of-concept that could eventually become useful.

btown• 12 years ago

If the finance industry (which is similarly large-investment and high-risk) can begin to use functional programming for critical applications, then I can see hardware moving towards it as well. If tools like Clash can be made to emit human-readable VHDL, I can see that as a path forward towards adoption.

zhemao5• 12 years ago

About EE conservatism in regards to software tools, this is mainly because we are highly restricted in what tools we can use by the platforms we have to design for. If you want to use a specific FPGA or a specific ASIC process, you have to use the tools that the FPGA vendor or ASIC foundry officially supports.

cantankerous2• 12 years ago

For such a mission critical application (hardware design) my mind is blown by how laughably bad the HDLs are when compared to modern programming languages. Chunks of the languages aren't synthesizeable, and which bits are/aren't are not consistent across vendors. There's also IEEE standards that nobody reeeally seems to care about too much. Additionally, it's not clear from a syntax point or a types point whether or not the code you will be writing is synthesizable. You just need to "know" ahead of time. It's terrible! It makes this whole field really obtuse and hard to enter from a design standpoint.

The field really needs some fresh blood or dare I say "disruption". I'm glad people are trying to make things better.

mikhael• 12 years ago

without having looked at it in much detail, does anyone know how/whether this is related at all to bluespec (http://en.wikipedia.org/wiki/Bluespec,_Inc.)?

knz422• 12 years ago

It's not related to bluespec. (cf my other comment in this thread)

akuma73• 12 years ago

There's already a commercial functional hardware description language called Bluespec. http://en.wikipedia.org/wiki/Bluespec,_Inc.

knz422• 12 years ago

Bluespec has a strange story: initially it was developed like Clash, as a subset of Haskell that could be translated to a HDL. However its users hated the Haskell syntax, so the Bluespec designers added a layer of syntax on top to make it look like more a HDL, and they also downplayed the powerful type system for adoption.

Since then, Bluespec has not become too popular, but Haskell has. Clash may have a chance.

aninhumer3• 12 years ago

I work with Bluespec. It's miles better than Verilog, but coming from a Haskell background, I can't help but feel disappointed with the limitations their alternative syntax puts on my ability to abstract things. (No lambdas, no do-notation, needlessly verbose sum types)

I'm also not really convinced by their hardware model (Guarded Atomic Actions). In practice, I've found that it leads to very disjointed flow control, and forbids what seem like intuitive designs.

sshine• 12 years ago

I did my bachelor's project on translation between functional HDLs that were also reversible, i.e. only describing total, bijective functions. The idea of functional HDLs goes back to at least the 1970s, and the coolest language I found was 𝜇FP by Mary Sheeran. It was an algebraic VLSI design language where logical gates as combinators are the only language constructs.

jberryman• 12 years ago

That sounds cool. I don't know anything about HDLs, but can you explain why you might want your functions to be bijective? What does that give you in hardware?

pseudonom-• 12 years ago

Maybe for reversible computing? [0]

[0] https://en.wikipedia.org/wiki/Reversible_computing

sitkack4• 12 years ago

Cool. Could you fill your post in with relevant links. I really dig this stuff.

http://scholar.google.com/citations?user=zQ49M2sAAAAJ&hl=en http://www.cs.ox.ac.uk/publications/publication3787-abstract...

sitkack4• 12 years ago

This looks really interesting http://www.cs.ru.nl/P.Achten/IFL2013/symposium_proceedings_I...

helpbygrace2• 12 years ago

I am hardware engineer in this industry. And I know Haskell and made my site with Haskell language. But I do not understand why Haskell is used to hardware design.

Designing hardware is much more important than describing hardware logic itself. IMO, VISIO and Excel are the tools to design hardware logic not Verilog nor like this CLaSH.

But, If this kind of HDL can be used along with Verilog, it might be helpful to build verification IPs.

zhemao5• 12 years ago

Wait, so what are you using to describe the circuit on the logic or RTL level? Do you have VLSI engineers using Cadence or something? From my understanding, using Verilog in ASIC design (and not just verification) is pretty widespread in industry.

platinum1• 12 years ago

I think what he's saying is the architectural decisions outweigh the implementation language.

When I was taught Verilog for IP implementation, one thing I noticed is that people get caught in the trap of trying to abstract away the hardware or approach it from a higher level. Haskell/Verilog 2001/SystemVerilog all give us tools to do this. However, when trying to make real silicon, you need to understand what is actually getting built (i.e. know exactly how many flip flops you're creating and how they fan out) and then use the language to describe it. If you use a 'for' loop to try to do computation, as you might in a programming language, you could end up with something entirely unexpected or unsynthesizable.

Traditionally you first design your module conceptually on a whiteboard (or Excel, Viso, etc.), then implement it in an HDL. Because of the influx of software engineers trying to get into hardware (via FPGAs, etc.), there has been a trend in trying to obfuscate away the details of the implementation, and this can cause a lot of confusion.

That said, I've heard of projects that already translate native Haskell to HDL with some success. I'm not a programmer so I don't claim to understand if it's a good idea, but I still think understanding exactly what's being output is important to knowing if it can perform in a reasonable way, especially if you're doing something of any complexity.

smackay• 12 years ago

In a former life (a long time ago), I used ELLA for designing processors. It was a pretty decent functional language. Great at abstracting components or subsystems and infinitely better than modelling stuff with C.

IIRC European Silicon Structures used to offer it as a part of their toolset when VLSI design was young and hot.

https://en.wikipedia.org/wiki/ELLA_%28programming_language%2...

CLaSH: A functional hardware description language

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