QOTD - Twitter Learning Scala


Several of us engineers at Twitter, Inc. are learning Scala as the language in which to develop new components for our system.


From Graceless Failures: Hello World

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Lists and arrays in Dart

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Converting Array to List in Scala

Now, this has to have a built-in somewhere in Scala , because it just seems too common. So, how to convert an Array to a List in Scala? Why do I need this? I needed to drop to Java for some functionality, which in this case returns an Array. I wanted to get that Array into a List to practice my functional programming skillz. **Update**: I figured out how to convert Arrays to Lists the Scala way. Turns out it's a piece of cake. val myList = List.fromArray(Array("one", "two", "three")) or val myList = Array("one","two","three").elements.toList The call to elements returns an Iterator , and from there you can convert to a List via toList . Nice. Because my first version wasn't actually tail recursive, what follows is a true tail recursive solution, if I were to implement this by hand. The above, built in mechanism is much better, though. object ArrayUtil { def toList[a](array: Array[a]): List[a] = { d
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Null-aware operators in Dart

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Three new language features just landed in the latest dev channel build of the Dart ! Collectively known as null-aware operators , these new features will help you reduce the code required to work with potentially null objects. I'm excited for these new abilities, because typing less is always a good thing. Read on to learn more, and be sure to try these new features on Dart Pad . ?? Use ?? when you want to evaluate and return an expression IFF another expression resolves to null. exp ?? otherExp is similar to ((x) => x == null ? otherExp : x)(exp) ??= Use ??= when you want to assign a value to an object IFF that object is null. Otherwise, return the object. obj ??= value is similar to ((x) => x == null ? obj = value : x)(obj) ?. Use ?. when you want to call a method/getter on an object IFF that object is not null (otherwise, return null). obj?.method() is similar to ((x) => x == null ? null : x.method())(obj) Yo
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