nt@ritsuko-ubnt:~/data/vex/VexRiscv-verilog$ sbt compile

java - sbt编译播放框架应用程序错误 - 堆栈内存溢出

HashMap defines getOrElseUpdate, += HashMap API. scala> val numbers = collection.mutable.Map(1 -> 2) numbers: scala.collection.mutable.Map[Int,Int] = Map((1,2)) scala> numbers.get(1) res0: Option[Int] = Some(2) scala> numbers.getOrElseUpdate(2, 3) res54: Int = 3 scala> numbers res55: scala.collection.mutable.Map[Int,Int] = Map((2,3), (1,2)) scala> numbers += (4 -> 1) res56: numbers.type = Map((2,3), (4,1), (1,2)) 2011-05-29 · Scala is amazing! It allows us to pass a function to getOrElseUpdate in case the value hasn’t already been evaluated. So f(x) is only evaluated iff the key x is not available. Note we call this a Memoize1 class since it extends Function1, i.e., a function that takes 1 argument. In this tutorial, we’ll learn how to use Play’s caching API with Scala.

Getorelseupdate scala

All Feb 24, 2016 Scala allows the special keyword lazy in front of val in order to change the val to one that is lazily initialized. While lazy initialization seems Our elegant styles are featured in over 800 boutiques around the world. SCALA designs come from the head and hearts of the tailors, beaders and designers. The factory creates 'Some(x)' if the argument is not null, and 'None' if it is null. The 'getOrElse(Default)' method goes into the Scala class hierarchy… Return optional values from a function with the Option class. Use None, isDefined , get and getOrElse. Li HaoyiLi Haoyi graduated from MIT with a degree in Computer Science and Engineering, and since then has been a major contributor to the Scala community.

In this tutorial, we’ll learn how to use Play’s caching API with Scala.

Build scala_library complains java.lang.ClassFormatError

The 'getOrElse(Default)' method goes into the Scala class hierarchy… Return optional values from a function with the Option class. Use None, isDefined , get and getOrElse. Li HaoyiLi Haoyi graduated from MIT with a degree in Computer Science and Engineering, and since then has been a major contributor to the Scala community. The last item among the control abstraction is the for expression.

Scala: HashMap med olika datatyper för olika nycklar möjligt?

The scala package contains core types like Int, Float, Array or Option which are accessible in all Scala compilation units without explicit qualification or imports.

Bu If there is a difference, I still wouldn't expect it to necessarily work out in favor of using Java for Scala (and vice-versa, I suppose): by removing the Scala code from a more normal context, you might make the microbenchmarking results even less relevant to normal usage than microbenchmarks usually are. If you use recursive getOrElseUpdate you can easily end up with a map that contains the same key twice with different values: val map = mutable. Map [ String, String ] () map.getOrElseUpdate ("key", { map.getOrElseUpdate ("key", "value1") "value2" }) map The second call could come from another place in the application this is just a sample. Scala’s Predef object offers an implicit conversion that lets you write key -> value as an alternate syntax ms getOrElseUpdate (k, d) If key k is defined in map Transform the builders into their results in a pass over the mutable Map before handing it to immutable.HashMapBuilder.addAll which already has an optimized path when the operation is a mutable.HashMap. Avoid lambda allocation in getOrElseUpdate call Avoid intermediate Tuple2 instances when iterating through the mutable map.
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As discussed above, the getOrElseUpdate () method retrieves the specified tweets from the cache if they exist, otherwise, it calls our wrapper for the Twitter API to retrieve the latest values. This is a very common usage pattern for any cache. This one API call will probably suffice for the great majority of applications.

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But it turns out that Scala collections already provide the getOrElseUpdate method on mutable maps. The 8 lines above translate simply into: 1 2. def getModelState(modelPrefixedId: String) = modelStates. The getOrElseUpdate is useful for accessing maps that act as caches. Say you have an expensive computation triggered by invoking a function f : scala> def f(x: String) = { println("taking my time."); sleep(100) x.reverse } f: (x: String)String The getOrElseUpdate is useful for accessing maps that act as caches. Say you have an expensive computation triggered by invoking a function f : scala> def f(x: String) = { println("taking my time."); sleep(100) x.reverse } f: (x: String)String Since we supported 2.10 we included our own simple atomic implementation.