x/playground: support for syntax highlighting

[dackon]

Currently, the playground is yellow background and black text, make it difficult to read the codes. Can you make codes colorful and bring editor to playground (like Wandbox) ?

[ALTree]

This was asked in the past. The most relevant discussion is at #28539.

To sum it up:

• the tour (https://tour.golang.org) has syntax colouring powered by CodeMirror (a rather beefy js lib)
• the playground code doesn't use CodeMirror and has no syntax colouring
• Apparently, codemirror is huge and it was decided not to add it to the playground, which is currently very simple (see final decision at x/playground: synchronize editor library with tour #18723)
• Adding colouring to the playground has been on the table (see my comment at x/playground: add code highlighting #28539 (comment)), but since it was decided not to use CodeMirror in the playground, we would need to either use a lightweight library or implement it from scratch

Essentially: it appears that adding syntax colouring for the playground would be okay, but someone needs to do the work and without using a beefy 3rd party lib like the one the tour uses.

[dackon]

Duplicate of #28539.

[ALTree]

#28539 is closed. This should be left open as the canonical reference for this work.

[beoran]

I think we could base ourselves on MicroLight: https://asvd.github.io/microlight/ , but change it so it recognises Go code only specifically. This also has the advantage that it highlights syntax without using color, only using font effects or a literal highlight effect.

[WoodpeckerBaby]

If it can be made to look like the default vscode, that would be great.

[subygan]

Is this issue still open? I would like to take a stab at this.

[beoran]

It is still open but ALTree has requested that this should be implemented using a very light weight library. That's why I proposed MicroLight which has the advantage that it is tiny and it also works also for color blind people like myself because it uses syntax styling instead of colors.