optiondesc.nim

import options, typetraits, sugar, typeinfo


template `?`(T: typedesc): typedesc =
  Option[T]

type

  Bar = ref object
    baz: int

  Foo = ref object
    bar: ?Bar

  mapper[T, R] = proc (val: T): R {.noSideEffect, gcSafe, locks: 0.}

func bar(foo: Foo): ?Bar = foo.bar
func baz(bar: Bar): int = bar.baz
template `?.?`[T](a: Option[T], b: untyped): untyped =
  a.flatMap(proc (val: T): untyped = val.b)

template `?.`[T](a: Option[T], b: untyped): untyped =
  a.map(proc (val: T): untyped = val.b)

let foo1: ?Foo = some(Foo(bar: some(Bar(baz: 10))))
let foo2: ?Foo = none[Foo]()
let foo3: Foo = Foo(bar: none[Bar]())

discard `?.?`(foo1, bar)
echo foo2?.?bar?.baz
echo foo3.bar?.baz