SplitWithUnion.ts

// This is tricky because you cannot do Str extends `${infer Before}${UnionOfSep}${infer After}` ...
type Split<Str, UnionOfSep extends string, CurrentWord extends string = "", Output extends string[] = []> =
  Str extends `${infer First}${infer Rest}`
    ? First extends UnionOfSep
      ? Split<Rest, UnionOfSep, "", [...Output, CurrentWord]>
      : Split<Rest, UnionOfSep, `${CurrentWord}${First}`, Output>
    : [...Output, CurrentWord];