A code sample from the article http://joshwulf.com/blog/2020/02/functional-refactor/

deploy-refactor-hypothetical.ts

const filereader = wf =>  typeof wf === 'object' ? wf : read(wf)

const read = filename => fs.existsSync(filename) ? 
      { buffer: fs.readFileSync(filename) } : 
      { error: filename }

const outcomes = workflows.map(filereader)

const { error, buffer } = outcomes.reduce((acc, o) => o.error ? 
    { error: [...acc.error, o.error], buffer: acc.buffer } :
    { error: acc.error, buffer: [...acc.buffer, o.buffer] }, 
    { error: [], buffer: [] })

if (error.length > 0) { 
  throw new Error(`Could not find files: ${error.join(', ')`})
}

deploy(buffer.map(makeRequestFromBuffer))