What is the more concise way to write `if (arg == ...

# stdlib

[Mark]

What is the more concise way to write if (arg == null) null else myfun(arg)? I can only think of arg?.let { myfun(it) } ?: null but this seems less readable to me.

[gildor]

arg?.let(::myFun)
You don’t need ?:

[Mark]

ah yes, in this case arg?.let { myfun(it) } so would let be the appropriate function to use?

[gildor]

if you need a concise way, yes

[gildor]

but it still not so much readable, requires little bit time to understand, but if you use this approach a lot, it’s actually nice idiom if you use it a lot, especially with method reference

[Mark]

Ok, thanks. I wonder about creating an extension function: MyArgClass.myfun() = this?.let {myfun(this)} so I can then do arg?.myfun()?

[Mark]

or is that super-weird!

[gildor]

depends on case I suppose. If you have a lot of such usages, why not.
It’s like any other toSomething functions, including stdlib

[Mark]

Another alternative would be to let myfun() accept a null arg and return null in that case. Is there some general way (contracts?) that a function can declare that a null arg will return null result?

[voddan]

IMHO if a function accepts a null it should deal with it more intelligently than returning another null immediately. In your situation an extension on a not-null type is the most obvious way IMO arg?.myFunc()

[hmole]

I think run instead of let looks more concise

[gildor]

you cannot use run with method reference