Interactive Phel REPL via PHP-WASM

[jasalt]

As example, Janet has a nice WebAssembly based REPL on the front-page https://janet-lang.org/. For Phel this could be achieved via PHP-WASM.

I did some earlier experimentation with it proving that the setup can work and it's not too complicated. I think it should be even simpler with the standalone Phar distribution now as a single file can be copied to the WASM "memory" and evaluated instead of workarounds I had to go through to get the full vendor/ path included with the autoloader functionality here phel-lang/phel-lang#816.

Basic version could simply load the static files required for the REPL to the front page template.

More fancy way that comes to mind would be to wrap it into Zola shortcode which could allow embedding it in different parts across the site with different placeholder contents but would require making sure multiple instances on one page wouldn't conflict e.g.

This could be a tutorial markdown file explaining some concept and 
following would inject Phel REPL in place with initial code for evaluation:

{% repl() %}
(for [x :in [1 2 3]]
  (inc x))
{% end %}

[jasalt]

Uniter could be another route also but I doubt how successful Phel transpiled to PHP transpiled to JavaScript would be, hehe. Would be fun to try though. It is used in Klipse that has browser evaluation support for many languages. Those might have some useful ideas regarding the REPL UI though.

[kambo-1st]

My few cents, as I tried to pack the PHAR file:

• The readline extension used in the REPL is not compatible with Emscripten (used for compiling the PHP interpreter to WebAssembly), so the REPL will need some work.
• I had to patch the PHAR to remove the shebang from the main entry point.
• The CLI in the PHAR is using exec (or something similar), and this will fail in WebAssembly.

Probably the best approach would be to expose an API of Phel as "libphel." Is there something like that @Chemaclass ?

[kambo-1st]

FYI: I looked into how Janet implements this (https://janet-lang.org/). They expose C functions repl_prompt and repl_input from webassembly , and the REPL itself is written in JS (simple yet effective)

[kambo-1st]

It ain’t much, but it’s honest work! (not a true REPL, just run the code from editor)

Public demo in upcoming days!

[kambo-1st]

Feel free to check out the demo at:
https://kambo-1st.github.io/phel/

It’s still extremely rough around the edges, as many things need to be fixed or improved. For example, it’s currently slow and large, and I’m not sure if it works on mobile devices. The silver lining is that only minimal changes to the source code are needed, and with prebuilt PHP the packaging process itself can be done entirely in pure PHP. I’ll now focus on automation and further optimization.

[Chemaclass]

On my pixel phone is not working, but it was working (the basic example run) on the laptop