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Comment by angleofrepose | Hacker News Reader

Off topic, but I’m wondering if anyone attracted to this topic could help me understand why JavaScript doesn’t have macros.

I’m aware of much conversation around dismissing macros, often in the context of bad dev experience — but this sounds like a shallow dismissal to me.

At the end of the day, we have some of the results of macros in the JavaScript ecosystem, but rather than being supported by the language they are kicked out to transpilers and compilers.

Can anyone point me to authoritative sources discussing macros in JavaScript? I have a hard time finding deep and earnest discussion around macros by searching myself.

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Interpreted languages rarely have macros.

But more importantly, do you really want script tags on webpages defining macros that globally affect how other files are parsed/interpreted? What if the macro references an identifier that's not global? What if I define a macro in a script that loads after some other JavaScript has already run? Do macros affect eval() and the output of Function.prototype.toString?

Sure, you could scope macros to one script/module to prevent code from blowing up left and right, but now you need to repeat your macro definitions in every file you create. You could avoid that by bundling your js into one file, but now you're back to using a compiler, which makes the whole thing moot.

It turns out there might actually be a benefit of the compilation step which has been introduced now that everyone uses Typescript... would be really interesting to see macros get added, though I suspect it's too far away from Typescript's mandate to add as few new features on top of Javascript as possible

Macros don't really make sense in JS runtime spec. Since you can mostly already achieve macro level features by using eval or new Function, but it's not very efficient. Macros make most sense at build time, and there have been a few attempts at generalized build macros with various bundlers / transpiler plugins. I think the space needs more time to mature. I'm optimistic that we'll eventually see some sort of (un)official macro spec emerge.

You could start here: https://github.com/search?q=org%3Atc39%20macro&type=code

A great resource that I should have found on my own. Thank you. I’ll look through this later. Giving it a quick glance now I see some of the same language I see other places; here that macros are “too far.”

I don’t know why macros are approached with apprehension. As I briefly get at in my first comment, I’m aware of a lot of dismissals of macros as a tool, but those dismissals don’t make sense to me in context. I’m missing some backstory or critical mind-share tipping points in the history of the concept.

What could be a good set of sources to understand the background perspective with which TC39 members approach the concept of macros?

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