In this blogpost by James Iry, he writes: Plus, Scala has an \"option\" method that promotes a value to either Some(value) or None depending on whether it\'s null or not ...
开发者_高级运维Suppose I have a method session.get(str: String): String but you don\'t know whether it will return you a string or a null, because it comes from Java.
Why does this construction cause a Type Mismatch error in Scala? for (first <- Some(1); second <- List(1,2,3)) yield (first,second)
how is meant to work Option monad? I\'m browsing the scala api and there is an example (I mean the second one),
say, I have a bunch of \"validation\" functions that return None if there is no error, otherwise it returnSome(String) specifying the error message.Something like the following ...
I have a list l:List[T1] and currently im doing the following: myfun : T1 -> Option[T2] val x: Option[T2] = l.map{ myfun(l) }.flatten.find(_=>true)
For a while I have been struggling to integrate scala with java methods that might return null.I came up with the following utility w开发者_开发问答hich helps a lot:
Option is implicitly convertible to an Iterable - but why does it not just just implement Iterable directly:
I want to transform a List[Option[T]] into a Option[List[T]]. The signature type of the function is def lo2ol[T](lo: List[Option[T]]): Option[List[T]]
As a result of articles I开发者_如何学Python read about the Option class which helps you avoid NullPointerException\'s, I started to use it all over the place. Imagine something like this:
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