Comment by PaulHoule | Hacker News Reader

Comment by PaulHoule | Hacker News Reader

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What I want from YAML (or a competitor) is access to the concrete syntax tree.

For one of my art projects I make YAML files that describe the front side, back side, and web side of a "three sided card". I generate these out of several templates, currently using ordinary string templating.

I'd love to be able to load a YAML file and add something programatically to the list and have the list stay in the same format that it was in, so if it was a

   [1,2,3]

list I get

   [1,2,3,4]

if it was a

   - 1
   - 2
   - 3

list I want

sadly I'm the only one who thinks this way.

In JavaScript, use https://www.npmjs.com/package/yaml for this:

    import assert from 'assert'
    import { parseDocument } from 'yaml'
    
    const flowDoc = parseDocument(`[1,2,3]`)
    flowDoc.add(4)
    assert(flowDoc.toString(), '[ 1, 2, 3, 4 ]\n')
    
    const blockDoc = parseDocument(`\
    - 1
    - 2
    - 3`)
    blockDoc.add(4)
    assert(
      blockDoc.toString(),
      `\
    - 1
    - 2
    - 3
    - 4
    `
    )

You are not the only one. But even if you find a library for YAML AST transformations for your language. What ever other language uses your YAML probably doesn't have it.

E.g. I tried exactly the same thing, and it was quiet difficult with Rust. Because the way to parse it usually is with serde and it just removes the AST of course.

In the end I gave up, and just used JSON for my use case.

https://yaml.readthedocs.io/

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