[Haskell-cafe] Well typed OS

[Will Yager]

> On Oct 20, 2018, at 09:11, Vanessa McHale <vanessa.mchale at iohk.io> wrote:
>  I would hesitate to use
> Haskell in the embedded context or for hardware-level stuff. I presume
> GHC's approach to laziness has a role in this.

There’s a bit of a complication here. It’s true that standard GHC generated code is unsuitable for hard-real-time/embedded environments (although I would argue that it’s actually fine for general purpose OS programming). However, as far as hardware goes, the semantics of (a non-monomorphically-recursive subset of) Haskell is actually a surprisingly close match for the semantics of hardware (as in LUTs and flip-flops, not as in random microcontrollers). 

This is the basis of projects like Clash (Haskell to HDLs).  I imagine one could extend the clash approach to generate allocation-free assembly from the same (large) subset of Haskell. 

> 
> I don't have much experience with OCaml but my experience with ATS is
> that it's very much possible to have functional, ML-style programming
> without a runtime or even dynamic memory allocation.
>> 

It’s possible to write low-allocation (I wouldn’t call it “allocation free” - usually just the hot loops don’t allocate) OCaml with the standard tools. However, it requires a fairly non-idiomatic style. 

—Will