export const concatCurryer = pre => cur => {
  const preToConcat = Array.isArray(pre) ? pre : [pre]
  const curToConcat = Array.isArray(cur) ? cur : [cur]
  return [...preToConcat, ...curToConcat]
}

// Examples
const arr1 = [{ val: "a" }, { val: "b" }]
const arr2 = [{ val: "c" }, { val: "d" }]
const obj1 = { val: 1 }
const obj2 = { val: 2 }

concatCurryer(arr1)(arr2) // [{ val: "a" }, { val: "b" }, { val: "c" }, { val: "d" }]
concatCurryer(obj1)(obj2) // [{ val: 1 }, { val: 2 }]
concatCurryer(arr1)(obj1) // [{ val: "a" }, { val: "b" }, { val: 1 }]

axios("http://some/api")
  .then(firstResult => {
    const firstResp = firstResult.data // { val: "first" }
    const concatter = concatCurryer(firstResp)
    
    axios(`http://some/other/api/${firstResp.val}`)
      .then(secondResult => {
        const secondResp = secondResult.data // { val: "second" }
        
        return concatter(secondResult.data) // [{ val: "first" }, { val: "second" }]
      })
  })