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Comment by yoav_lavi | Hacker News Reader

Author here,

1. A reverse compiler is one of the 'maybe' features (see the table in the README), it's something I'd like but would essentially be an entire compiler so it's non trivial

2. The plan is to make Melody available as a compile step (like e.g. SASS) with no runtime overhead or as a Rust crate. You could do the compilation at runtime but other than including variables in the pattern I'm not sure if it'd have a benefit over compile time transforming, + it'd have a performance impact.

Thank you!

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No dramas, understood re 1 it's no doubt beyond trivial to create a bidirectional transpiler. I wouldn't even know where to begin so good work on what you've managed so far.

Re 2, shouldn't be a problem as we already have build processes in place. Most projects I work on have npm build steps, I'm not sure how that figures in with rust (I really need to get off my butt and check it out sometime), but if it could be pulled in as an npm dependency that would work. If it could be done inline even better (e.g. inline melody within a JS file, compiles to the expression inline...)

Anyway good job again so far, have followed the repo, all the best once more!

Thank you!

>If it could be done inline even better

I've been thinking of using a tagged template based mechanism (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...) so no special editor support is needed and then transpile to a normal regex (similar to how htm handles it's syntax with no runtime, https://www.npmjs.com/package/babel-plugin-htm) but I'm not working on that part of the process yet so it may change.

If Melody does end up using the tagged template mechanism it may end up looking something like this:

  import melody from "melody";

  const batmanRegex = melody`
    16 of "na";

    2 of match {
      <space>;
      "batman";
    }
  `;

That would transpile to:

  const batmanRegex = /(?:na){16}(?:\sbatman){2}/;

Backticks would need escaping but otherwise it'd be normal Melody syntax

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