Would be super simple, essentially wrap a module into (x, f) => f(x) where f(x) is true or f(x) is false. x can then be something like

require('is-my-schema-valid')({
  required: true,
  type: 'object',
  properties: {
    rna-fastq: {
      required: true,
      type: RegExp
      pattern: new RegExp(`^${speciesName}.${run}.fastq.gz`)
    }
  }
})

However just realized perhaps is-my-schema-valid cannot compare RegExp objects as they are not by default in JSON.stringify(). @mafintosh, how difficult to extend the plugin, perhaps similar like replacer and reviver functions to faciltate comparisons of objects?

Taking a hint from how webpack lets you choose loaders based on regexing (somewhat implicit understood) filetypes, could apply arrows of validators to specific files, or subtrees of resolved output objects.