Add support for optional chaining

[samber]

Some languages like Typescript or Swift offer a very cool syntactic sugar a?.b?.c?.d?.e.

In Go, we need to write a condition similar to: a != nil && a.b != nil && a.b.c != nil.

I create this issue for discussing a new helper.

In PR #106, I suggest an implementation called Safe:

type a struct {
    foo *string
}
type b struct {
    a *a
}
type c struct {
    b *b
}

v := &c{
    b: &b{
        a: nil,
    },
}

foo, ok := lo.Safe(func() string { return *v.b.a.foo })
// "", false

Calling *v.b.a.foo will panic, but this nil pointer error will be caught by lo.Safe. Other exception won't be caught.

This implementation is much more "typesafe" than something like lo.Safe(a, ".b.c.d")

WDYT?

[wirekang]

Safe is very good function. But can we implement real optional chaining without modifing Go Compiler? I mean, if a.b.c panics because a.b is nil, the 'Optional Chaining Function' should returns a. But how can we get information of a?

[CorentinClabaut]

This looks nice. It's verbose, but without a language update it looks like that's the best option. I was thinking, it might be helpful to also have a function with a default value in case of panic like func SafeOr[T any](cb func() T, fallback T) T WDYT?

[renom]

Catching out of bounds error would make sense too