message: Improve Identifier highlighting
diff: -// Check out some other Prism highlighters for inspiration:
  -//
  -// https://github.com/PrismJS/prism/blob/master/components/prism-haskell.js
  -// https://github.com/PrismJS/prism/blob/master/components/prism-rust.js
  -// https://github.com/SassDoc/prism-scss-sassdoc/blob/master/prism-scss-sassdoc.js
  +/**
  + * Pikelet Prism syntax highlighting.
  + *
  + * Check out the Prism language definition docs for more help in extending this:
  + * https://prismjs.com/extending.html#language-definitions
  + *
  + * It might also be helpful to look at some other Prism highlighters for inspiration:
  + *
  + * - https://github.com/PrismJS/prism/blob/master/components/prism-haskell.js
  + * - https://github.com/PrismJS/prism/blob/master/components/prism-rust.js
  + * - https://github.com/SassDoc/prism-scss-sassdoc/blob/master/prism-scss-sassdoc.js
  + */
  Prism.languages.pikelet = {
  // Comments.
  @@ -31,10 +38,17 @@ Prism.languages.pikelet = {
  pattern: /b?'(?:\\(?:x[0-7][\da-fA-F]|u{(?:[\da-fA-F]_*){1,6}|.)|[^\\\r\n\t'])'/,
  alias: "string"
  },
  + // Identifiers
  + identifier: {
  + pattern: /\b(?:[a-zA-Z][a-zA-Z0-9\-]*)\b/,
  + greedy: true,
  + inside: {
  // Keywords
  - keyword: /\b(?:fun|Record|record)\b/,
  + keyword: /^(?:fun|Record|record)$/,
  // Builtins
  - builtin: /\b(?:Type|Bool|true|false|U8|U16|U32|U64|S8|S16|S32|S64|F32|F64|String|Char|Array|List)\b/,
  + builtin: /^(?:Type|Bool|true|false|U8|U16|U32|U64|S8|S16|S32|S64|F32|F64|String|Char|Array|List)$/
  + }
  + },
  // Numeric literals
  number: [
  /(-|\+)?\b(?:0b[01](?:_?[01])*)(?:_)?\b/,
  