import std/sugar
import fp/maybe
import results

func last*[T](xs: seq[T]): Maybe[T] =
  if xs.len == 0:
     nothing(T)
  else:
    just(xs[^1])

template isSome*(self: Result): bool = self.isOk()
template isNone*(self: Result): bool = self.isErr()

proc findMaybe*[T](xs: seq[T], fn: T -> bool): Maybe[T] =
  for x in xs:
    if fn(x):
      return Just(x)
  return Nothing[T]()

proc findMaybeFn*[T, B](fns: seq[T {.nimcall.} -> Maybe[B]], val: T): Maybe[B] =
  for fn in fns:
    let res = fn(val)
    if res.isDefined():
      return res
  return Nothing[B]()

proc notNegative*[int](x: Maybe[int]): Maybe[int] =
  ## Maps nil object to nothing
  x.filter(i => i >= 0)

when isMainModule:
  echo @[
  (x: int) => (if x == 2: Just("foo") else: Nothing[string]()),
  ].findMaybeFn(2)

  assert last(@[1,2,3]) == just(3)
  assert last[int](@[]) == nothing(int)