[libre-riscv-dev] nmigen frustrations make me want Rust

[Luke Kenneth Casson Leighton]

On Monday, March 18, 2019, Jacob Lifshay <programmerjake at gmail.com> wrote:

> One additional option is to add nmigen interop support to the Rust HDL.
> Rust has a rather non-verbose binding to python: https://pyo3.rs/


It looks like it's a crude/lowlevel near-direct interface to the c python
module API. I recognise the data structure names and the "GIL". Global
something Lock.

It'd be a handful. The python c interface has some crucial conventions
which if not obeyed result in crashes and memory leaks. It's a pain to work
with, only worth it if you seriously need speed.

L.


> On Sun, Mar 17, 2019, 07:18 Jacob Lifshay <programmerjake at gmail.com>
> wrote:
>
> > On Sun, Mar 17, 2019, 07:14 Luke Kenneth Casson Leighton <lkcl at lkcl.net>
> > wrote:
> >
> >> Example of the polymorphic benefits of python which I plan to exploit is
> >> in
> >> the pipeline Stage API. Use m.d.comb += self.idata.eq(self.idata) and if
> >> odata is an object or a signal it does not matter.
> >>
> >> The API requirement becomes that if it is an object then the eq function
> >> must return a *list* of eq assignments of all of the signals within that
> >> class instance that will get the assignment of the idata object signals
> >> into odata.
> >>
> >> Strong typing actually massively interferes with this type of
> flexibility
> >> as it is unexpected and unanticipated legitimate *and desirable*
> behavior
> >> that not even the authors of nmigen could have predicted, and strong
> >> typing
> >> would prevent and prohibit unless explicitly envisaged, way, way in
> >> advance, which is almost impossible and impractical.
> >>
> > I think Rust can let you do that.
> >
> >>
> >> This type of powerful shoot-yourself-in-the-foot capability of python is
> >> just something that you need to put strict software engineering
> practices
> >> in place and adhere to them no matter what.
> >>
> >> 15 years ago I genuinely used to think that unit tests were a total
> waste
> >> of effort. Then for pyjamas (the python to javascript language
> translator)
> >> we accumulated well over 20,000 of them and it was the only way that we
> >> could safely make forward progress.
> >>
> >> As a team we managed some really quite significant fundamental
> redesigns,
> >> outputting completely different code, even with different performance
> >> characteristics.
> >>
> >> L.
> >>
> >>
> >> --
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> >>
> >
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