
Schism – A self-hosting Scheme to WebAssembly compiler - tosh
https://github.com/google/schism
======
ThatGeoGuy
First off: Neat project, I think this could actually turn into something super
cool, especially if it could be transpiled into from another source. Think
like CHICKEN, except instead of Scheme -> C -> binary, we could get $LANG ->
Schism -> WASM (here, my $LANG of choice could even be CHICKEN)

However, I find the choice of R6RS... odd. Is it not easier to target R7RS-
small or R5RS as a baseline to begin with? I know some people have problems
(or too much love) with R6RS for what may be described as religious reasons,
but I find it an extremely surprising choice here given that R7RS-small is
much simpler and easier to get right.

Likewise, the majority of R7RS-compatible libraries would be available for
free. That would add a lot for a high level language targeting WASM. Seems a
strange choice, maybe the author has documented this somewhere?

~~~
eholk
I haven't documented the choice of R6RS anywhere, so here is as good of place
as any.

The main reason was familiarity. R6RS is the Scheme I know best. I learned on
R5RS and moved on the R6 when it was the new hotness. I vaguely was aware of
R7 (I have friends that were on the standards committee), but didn't really
know much more than that it had happened.

There's a technical reason for choosing R6RS as well though. To me the
defining characteristic of R6RS is the library system. In my mind, this has a
pretty clear mapping to WebAssembly modules. Scheme libraries import some set
of identifiers and export another set. WebAssembly modules are the same way,
so I basically set it up so that Scheme exports and imports map directly only
WebAssembly exports and imports.

I'd definitely be open to supporting other Scheme versions in the future.

~~~
ThatGeoGuy
> There's a technical reason for choosing R6RS as well though. To me the
> defining characteristic of R6RS is the library system. In my mind, this has
> a pretty clear mapping to WebAssembly modules.

Well, this is a clear win for R6RS over R5RS, but R7RS has a much more
flexible and well-agreed upon module system. One of the things about R6RS
against its favour is that the module system never caught on with the major
Scheme implementations (Gauche, Gambit, CHICKEN, Racket), and everyone kind of
rolled their own. It's only in recent times that I've notice a lot more
activity converging around R7RS.

Nonetheless, thanks for responding. Familiarity is a reasonable enough reason
for choosing a standard.

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kuwze
I love the fact that they chose s-expressions for the textual representation
of WASM[0][1].

[0]: [https://developer.mozilla.org/en-
US/docs/WebAssembly/Underst...](https://developer.mozilla.org/en-
US/docs/WebAssembly/Understanding_the_text_format)

[1]:
[https://github.com/WebAssembly/design/blob/master/TextFormat...](https://github.com/WebAssembly/design/blob/master/TextFormat.md)

~~~
bcherny
Could you explain for the uninitiated?

~~~
icebraining
WASM supports two formats; a binary format, which is the recommended for
actually shipping to the browser, and a text format, mostly for humans to read
and edit programs.

The text format uses Lisp-style syntax, with parenthesis, e.g.:

    
    
        (func (param i32) (param i32) (result f64) ... )
    

This syntax is called S-expressions, and it has strong adherents and
opponents.

~~~
kazinator
No, only weak, misinformed opponents with low to no experience with
S-expressions.

------
tarcyanm
I wonder if they're aware of Ian Piumarta's Maru and Cola
([http://www.piumarta.com/software/](http://www.piumarta.com/software/)) -
which are also tiny and self-compiling (although use C and IA32 as a basis,
not JS).

~~~
eholk
I hadn't seen those before. Thanks for the link, they look pretty interesting!

------
bjoli
I can't wait to play with this when I get home! I loathe doing web
development. I just can't wrap my head around it, so whenever WASM gets in a
position where it can easily work with the DOM (preferrably with a decent GC),
I will be all over it :)

The project is in an interesting phase as well. Doing CPS transforms and
implementing macros (the only thing really hard about writing a scheme).

------
qwerty456127
Cool! BTW, there is so much LISP on HN, I just wish it could actually get some
momentum in the real world of production programming...

~~~
lilactown
I just got my whole team to switch to Clojure(Script), so... ;)

------
pjmlp
It looks quite cool.

For awhile I had the idea of applying "An Incremental Approach to Compiler
Construction" to WASM, but never followed up on that.

Congratulations.

------
tomcam
Somewhat unrelated question: would WebAssembly make a good intermediate
language? It looks more machine-independent than I expected.

~~~
davidgrenier
I'm confused, isn't that what WebAssembly has specifically been designed for?
Unless you mean something else by "intermediate language" than what I read as
"intermediate representation".

~~~
radarsat1
I think he means, not just for web stuff. Which, of course, exists:
[https://github.com/AndrewScheidecker/WAVM](https://github.com/AndrewScheidecker/WAVM)

~~~
tomcam
Cool! Thank you.

------
igorkraw
First thought I had: We finally have scheme running in the browser:
[https://brendaneich.com/2008/04/popularity/](https://brendaneich.com/2008/04/popularity/)

Then the comments pointed me to this

[http://www.biwascheme.org/](http://www.biwascheme.org/)

ah well

------
shaunxcode
Yes! Beneath the paving stones - the beach!!

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alexozer
Under 1000 lines, too?

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throwaway7645
Is there any chance Google might put more effort into this in the future?
Scheme in the browser would be awesome. I'm guessing it is just a Google
employee's pet project?

~~~
DannyBee
This is just a random googler side project. That's what the disclaimer means.
Any effort being put into it is by that person :)

~~~
throwaway7645
Sadly that's my assumption too.

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sdiupIGPWEfh
Been waiting for someone to do this. Glad to see there's still plenty of room
for contributions.

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VikingCoder
...why didn't they use github hosting, so we can actually see it running?

~~~
mirekrusin
Why didn’t you post pull request with it yet so we can all see?

~~~
VikingCoder
Configuring your github repro so that it CAN be hosted is not something you
can change through a pull request.

~~~
mirekrusin
It's just a branch with special name.

