This shows the current Syntax highlighting file for the Jux language, which tries to higlight function definitions, which has problems.

JuxBeta.YAML-tmLanguage

# [PackageDev] target_format: plist, ext: tmLanguage
---
name: Jux Syntax (Beta)
scopeName: source.jux-beta_syntax
fileTypes: [jux]
uuid: c2678932-0739-4006-bb20-30e38fe41dea
foldingStartMarker: '\s*\[\s*$'
foldingStopMarker: '\]\s*$'

patterns:
- include: '#comment'
- include: '#quotation_start'
- include: '#quotation_end'
- include: '#definition'
# - include: '#simple_definition'
- include: '#string'
- include: '#identifier'
- include: '#integer'

repository:
  comment:
    match: (?:^ *|\G *| +)((#).*\n?)
    captures:
      '1': {name: comment.line.number-sign.jux-beta_syntax}
      '2': {name: punctuation.definition.comment.line.jux-beta_syntax}
  quotation_start:
    name: "keyword.control.quotation.start.jux-beta_syntax"
    match: (\[)
  quotation_end:
    name: "keyword.control.quotation.end.jux-beta_syntax"
    match: (\])
  string:
    name: "string.quoted.double.jux-beta_syntax"
    begin: '"'
    end: '"'
    patterns:
      - name: constant.character.escape.jux-beta_syntax
        match: (\\.)
  identifier:
    name: "variable.language.jux-beta_syntax"
    match: ([a-zA-Z_][\w]*[?!]?)

  integer:
    name: "constant.numeric.jux-beta_syntax"
    match: ([+-]?\d+)
  # TODO: Fix this, if possible
  # mutliline-definitions are (nearly?) impossible in the tmLanguage.
  # We want this to match:
  # ```
  # "foo"
  #   ""
  #   [
  #    .. a program here..
  #   ]
  # def
  # ```
  # Most importantly, we only want it to match if the whole snippet exists; e.g. not make a string blue when no matching `def` is there.
  # 
  
  definition:
    name: "entity.other.function.jux-beta_syntax"
    begin: ("([a-zA-Z_][\w]*[?!]?)")
    end: (def)
    beginCaptures:
      '1': {name: "entity.name.function.jux-beta_syntax"}
    contentName: "support.constant.jux-beta_syntax"
    patterns:
    - include: '#comment'
    - include: '#quotation_start'
    - include: '#quotation_end'
    #- include: '#definition'
    - include: '#string'
    - include: '#identifier'
    - include: '#integer'
  # simple_definition:
  #   name: "entity.other.function.jux-beta_syntax"
  #   match: "def"