While using a Scala Stream to implement Fibonacci would automatically leverage memoization, one could also explicitly employ the very feature without Streams. For instance, by leveraging method getOrElseUpdate in a mutable Map, a memoize function can be defined as follows:

17/01/10 19:17:20 ERROR ShuffleBlockFetcherIterator: Failed to get block(s) from bigdata-hdp-apache1828.xg01.diditaxi.com:7337 java.lang.NullPointerException: group

Resolution. Remove these request types or add at least one field to the request type. Play Framework - The High Velocity Web Framework For Java and Scala. Note : getOrElseUpdate is not an atomic operation in EhCache and is implemented Scala parallel collections allow you to solve data parallelism problems in ms getOrElseUpdate(k, d), If key k is defined in map ms, return its associated value. scala> Map('a' -> 1, 'b' -> 2) res4: scala.collection.immutable.Map[Char getOrElseUpdate(2, 3) res54: Int = 3 scala> numbers res55: scala.collection. mutable.

Getorelseupdate scala

Given a new, mutable Scala Map : scala> var states = scala.collection.mutable.Map[String, String]() states ms getOrElseUpdate (k, d), If key k is defined in map ms , return its associated value. Otherwise, update ms with the mapping k -> d and return d . Removals:. AbstractMap.getOrElseUpdate(Map.scala:80) [error] at scala.reflect.macros. runtime.MacroRuntimes.standardMacroRuntime(MacroRuntimes.

Feb 11, 2021 HashMap.getOrElseUpdate(HashMap.scala:86) ~[scala-library-2.12.10.jar:?] at org.neo4j.cypher.internal.compiler.helpers.

/** * Convert this promise to a Scala future. *

* This is equivalent to FutureConverters.toScala(this), however, it converts the wrapped completion stage to * a future rather than this, which means if the wrapped completion stage itself wraps a Scala future, it will * simply return that wrapped future.

Can the highlighted with comment line be rewritten using the getOrElseUpdate method? P.S. I am only at the 4th part of the "Scala for the impatient", so please don't teach me now about functional Scala which, I am sure, can be more beautiful here. Thanks.

Runner.main(Runner.scala) Caused by: java.awt.HeadlessException at getOrElseUpdate(MapLike.scala:189) at scala.collection.mutable.AbstractMap. Feb 11, 2021 HashMap.getOrElseUpdate(HashMap.scala:86) ~[scala-library-2.12.10.jar:?] at org.neo4j.cypher.internal.compiler.helpers.

Notable packages include: scala.collection and its sub-packages contain Scala's collections framework mutable.HashMap getOrElseUpdate not reentrant in 2.12 Showing 1-3 of 3 messages. [scala-user] mutable.HashMap getOrElseUpdate not reentrant in 2.12: Jason Zaugg: @Jaimeloeuf yes, we're certain this bug is fixed, assuming you have new enough versions of everything, and scala/scala-seed.g8 certainly has new enough versions of things so this was a reasonable place to begin asking, but I think you want to move to https://users.scala-lang.org at this point and provide full details/transcript on what you're doing, to help folks spot what's going wrong While using a Scala Stream to implement Fibonacci would automatically leverage memoization, one could also explicitly employ the very feature without Streams. For instance, by leveraging method getOrElseUpdate in a mutable Map, a memoize function can be defined as follows: The following examples show how to use scala.collection.mutable.Map.These examples are extracted from open source projects. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. A quick hack to wrap Google Guava's cache with a slightly more scala-friendly API. The main goal is to have a getOrElseUpdate method that is actually thread safe, unlike the one on Scala's ConcurrentMap. [Redirected to scala-language since I'm not on scala-user.] Someone asked me recently why I'm against extending Function1 casually.
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This is the documentation for the Scala standard library. Package structure . 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. Notable packages include: scala.collection and its sub-packages contain Scala's collections framework mutable.HashMap getOrElseUpdate not reentrant in 2.12 Showing 1-3 of 3 messages. [scala-user] mutable.HashMap getOrElseUpdate not reentrant in 2.12: Jason Zaugg: @Jaimeloeuf yes, we're certain this bug is fixed, assuming you have new enough versions of everything, and scala/scala-seed.g8 certainly has new enough versions of things so this was a reasonable place to begin asking, but I think you want to move to https://users.scala-lang.org at this point and provide full details/transcript on what you're doing, to help folks spot what's going wrong While using a Scala Stream to implement Fibonacci would automatically leverage memoization, one could also explicitly employ the very feature without Streams.

· Type Safe. 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.
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Mutable Maps have a convenient getOrElseUpdate function, that allows you to look up a value by key, and compute/store the value if there isn't one already present: @ val m = collection.mutable.Map("one"-> 1, "two"-> 2, "three"-> 3) @ m.getOrElseUpdate("three",-1) // already present, returns existing value res87: Int = 3 @ m // `m` is unchanged res88: mutable.

The example code counts each word's occurrences in given input file: object Main { def main(args: Array[String]) { val counts = new scala.collection.mutable.HashMap[String, Int] val in = new Scanner(new File("input.txt")) while (in.hasNext()) { val s: String = in.next() counts(s) = counts.getOrElse(s, 0) + 1 // Here! This is typically logic you would write in Java, and it looks great in some ways: it uses pattern matching, the tuple arrow ( -> ), etc. 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.

Oct 28, 2019 createThroughDaemon(PythonWorkerFactory.scala:122) at getOrElseUpdate( BlockManager.scala:882) at org.apache.spark.rdd.RDD.

There are 4 solutions: Relax the contract of getOrElseUpdate to potentially allow evaluating the call-by-name parameter. Extract the getOrElseUpdate into another interface that concurrent maps do not inherit, but non-thread-safe maps like mutable.HashMap do. Have ParTrieMap throw an exception for getOrElseUpdate. retronym merged 3 commits into scala: 2.12.x from paplorinc: getOrElseUpdate Nov 22, 2016 Conversation 57 Commits 3 Checks 0 Files changed Conversation 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 ) = { igreenfield commented on Jan 28, 2018.

ms -= (k, l, m) Removes mappings with the given keys from ms as a side effect and returns ms itself. ms --= ks // not possible with Int counts.getOrElseUpdate(key, 0) += 1 // but with a modifiable counter counts.getOrElseUpdate(key, new Counter).increment Somehow I'm always expecting to have the following functionality with a mutable map (somewhat similar to transform but without returning a new collection and on a specific key with a default value): Note: getOrElseUpdate is not an atomic operation in EhCache and is implemented as a get followed by computing the value, then a set.