Optional version number in Squiggle files

[OAGr]

(Not urgent at all)

One issue that will emerge soon is backwards-breaking changes.

People currently write Squiggle code in online forums and similar. Nuno has pasted the relevant code directly on the EA Forum.

It could be great if people could tag the version of Squiggle they're using when writing something.

## squigglev0.1.3

mx(normal...

Vega does similar:

"$schema": "https://vega.github.io/schema/vega/v5.json",

Javascript

Apparently in JS, they take intense measures to not have breaking changes. The strategy is called "One Javascript".
https://exploringjs.com/es6/ch_one-javascript.html

However, if we were to commit to this, that would dramatically hurt experimentation early-on.

Python

In python, you can prefix files with,

#!/usr/bin/env python2.7

https://stackoverflow.com/questions/11170827/how-do-i-tell-a-python-script-to-use-a-particular-version

[OAGr]

Btw @umuro I'd be curious if you have any take on this. Is this sort of thing common in other languages that come to mind to you?

I imagine it's only an issue in early/small languages, that can actually have breaking changes.