Problems with ts

flip.ts

// Typescript can handle monomoprhic functions
const flip = <A, B, C>(f: (a: A) => (b: B) => C): ((b: B) => (a: A) => C) => b => a => f(a)(b)

const foo = (a: string) => (b: number) => a.length - b

// fooFlipped: (b: number) => (a: string) => number
const fooFlipped = flip(foo)

  // But can't handle polymorphic functions
  const concat = <A>(xs: Array<A>) => (a: A): Array<A> => xs.concat([a])

// concatFlipped: (b: {}) => (a: {}) => {}[]
const concatFlipped = flip(concat)

// ok but is awkward
const concatFlipped2: <A>(a: A) => (xs: Array<A>) => Array<A> = flip(concat)