For typical REPL usage and experimentation, importing the global ExecutionContext is often desired. This could be done in Scala 3.0, add a specific return type. Drops longest prefix of elements that satisfy a predicate. think of this artifact as an incubator: if we get evidence that these operations should be part of the core, Tests whether this collection is known to have a finite size. an immutable map consisting only of those key value pairs of this map where the key satisfies the predicate p. The resulting map wraps the original map without copying any elements. Making statements based on opinion; back them up with references or personal experience. Not the answer you're looking for? #1 I thought that a valof an immutable type is always safely immutable, but it's not. A future version will include a strict version of this method (for now, .view.mapValues(f).toMap). Spark mapValues() - Spark By {Examples} Tests whether the collection is not empty. But the mutable the method toString) of all elements of this collection are separated by the string sep. (Even if we wouldn't do #2, we'll need the same implementations). This collection as an Iterable[A]. The number of elements in this map, if it can be cheaply computed, -1 otherwise. developers guidance on how long a deprecated definition will be preserved. Well occasionally send you account related emails. Why add an increment/decrement operator when compound assignments exist? If this iterable collection is shorter than that, thisElem values are used to pad the result. true if ! well as the interaction between finalize and non-local returns Scala: Replace keys in a map with an object? we might eventually move them. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of init. For a non-strict collection such as, Note: many collection methods will not work on collections of infinite sizes. Strict collections have an overridden version of, the 'split function' mapping the elements of this iterable collection to an, a pair of iterable collections: the first one made of those values returned by, an implicit parameter defining a set of numeric operations which includes the, the product of all elements of this collection with respect to the, A type parameter for the binary operator, a supertype of, An option value containing result of applying reduce operator, Compares the size of this iterable collection to the size of another, The method as implemented here does not call, These operations are implemented in terms of, The returned iterable collection is made up of all elements, a iterable collection containing the elements greater than or equal to index, Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in, a pair consisting of the longest prefix of this iterable collection whose elements all satisfy, a pair of iterable collections consisting of the first, The Stepper enables creating a Java stream to operate on the collection, see, Note that this method is overridden in subclasses and the return type is refined to, the sum of all elements of this collection with respect to the, a iterable collection consisting only of the first, a iterable collection consisting only of the last, the longest prefix of this iterable collection whose elements all satisfy the predicate, a two-dimensional iterable collection of iterable collections which has as. might be kept longer to ease migration, but developers should not rely on this.). except that applyOrElse method can be implemented more efficiently. Then, I will show why I think The order of the elements is preserved. will mention the main deprecations, the motivations behind them, and their the first element of this iterable collection. We have introduced a few new operations. julienrf approved these changes. You can force it with .view.force, but it would be nice if the return type made it clear that it was a view. be preserved at least for the current major version. https://github.com/scala/scala-parser-combinators/pull/152, https://github.com/scala/scala-xml/pull/222, Some other examples are listed here: https://github.com/scala/community-builds/issues/710. Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. Test whether the dynamic type of the receiver object is T0. I have several immutable map records like : I need to identify the "name" key for each record and check its value.If value is "Jane" , I need to replace with "Doe" and update the map record. Other packages exist. an option value containing the value associated with key in this map, or None if none exists. By clicking Sign up for GitHub, you agree to our terms of service and 7 both in terms of Votes and Watchers. A deprecation warning is issued upon usage of the annotated definition. All strict collections are known to have finite size. The good news is that the new design is more correct in the sense that you can For all partial function literals the compiler generates an applyOrElse implementation which avoids double evaluation of pattern matchers and guards. An annotation that designates that a definition is deprecated. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false. /** Transforms this map by applying a function to every retrieved value. Find centralized, trusted content and collaborate around the technologies you use most. Selects all elements of this view which do not satisfy a predicate. Remove outermost curly brackets for table of variable dimension. If the runtime type of the function is a PartialFunction then the other andThen method is used (note its cautions). the result of applying the fold operator op between all the elements and z, or z if this collection is empty. an option value containing the value associated with, Note: Implementations in subclasses that are not repeatedly iterable must take care not to consume any elements when. How to format a JSON string as a table using jq? @dragos said: Sometimes a deprecated element might be kept for more than a major By clicking Sign up for GitHub, you agree to our terms of service and One could still change the return type to be more specific, like MapView (which somebody should write) or sth. 1 2 m: scala.collection.immutable.Map[Int,Int] = Map(1 -> 1, 2 -> 2) scala> m . Scala's Predef object offers an implicit conversion that lets you write key -> value as an alternate syntax for the pair (key, value). You must change the existing code in this line in order to create a valid suggestion. a string representation of this collection. The static return type is Map Realistically, I think nothing will ever be done about this because it would break too much existing code that relies on the lazy behavior. Note that the success of a cast at runtime is modulo Scala's erasure semantics. Scala programming documentation. I would be in favour of adding mapValuesNow, which already exists on s.c.i.AnyRefMap and s.c.i.LongMap. Creating a Map Displays all elements of this collection in a string. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of tail. the result of inserting op between consecutive elements of this collection, going left to right: op( op( op(x1, x2) , xn-1), xn) where x1, , xn are the elements of this collection. the number of elements satisfying the predicate, a iterable collection consisting of all elements of this iterable collection except the first, a iterable collection consisting of all elements of this iterable collection except the last, the longest suffix of this iterable collection whose first element does not satisfy the predicate, a new view consisting of all elements of this view that satisfy the given predicate, an immutable map consisting only of those key value pairs of this map where the key satisfies the predicate, a new view consisting of all elements of this view that do not satisfy the given predicate, an option value containing the first element in the collection that satisfies, a new iterable collection resulting from applying the given collection-valued function, a new map resulting from applying the given collection-valued function, an implicit conversion which asserts that the element type of this iterable collection is an, a type parameter for the binary operator, a supertype of. Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n). * We could maybe also document how to perform this operation in a strict way (.view.filterKeys(p).toMap)? with value equality: if two value type instances compare The written text consists of the string representations (w.r.t. The since argument needn't be a date, in fact the docs specify it as "a string identifying the first version in which the definition was deprecated". My code is like this: I am using view.mapValues because .map is deprecated. Making certain operations lazy is extremely confusing. MapValues Identifying large-ish wires in junction box, Characters with only one possible next character. strict collections (such as List) and non-strict collections (such as Stream). Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference. @deprecated("Use view.filterKeys. the largest element of this collection with respect to the ordering ord. A duration DSL is available This simplifies cross-building projects. expression List(1).isInstanceOf[List[String]] will return true. TreeMap takes two type parameters (the type of keys and the type Example code (in scala REPL): scala> val x = Map("foo" -> 1, "bar" -> 2) x: scala.collection . The resulting function runs action(this(x)) where this is defined. ", "2.13.0"), override def view: MapView[K, V] = if (nonReadOnly) readOnlySnapshot().view else super.view, def filterKeys(p: K => Boolean): MapView[K, V] = new MapView.FilterKeys(this, p). Unless overridden, the default method throws a NoSuchElementException. either an implicit or explicit ExecutionContext to be provided: Although blocking is possible in order to await results (with a mandatory timeout duration): and although this is sometimes necessary to do, in particular for testing purposes, blocking I guess we should then also add filterKeysNow. the message to print during compilation if the definition is accessed, a string identifying the first version in which the definition was deprecated. You can find more details about that in This means that an element deprecated in some 2.13.x release will be preserved in confusion to the users. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply. The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). You can CanBuildFrom was used for good reasons, in particular the type That shown For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams. See hashCode in scala.Any. Solution. the element type of the returned iterable collection. re-implementing a ton of operations. or Option which are accessible in all Scala compilation units without explicit qualification or the type to which function g can be applied, a new function f such that f(x) == apply(g(x)). This method invokes the default method of the map if there is no mapping from the given key to a value. Zips this iterable collection with its indices. potential deadlocks and improve performance. The second choice sounds the most reasonable to me. List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)". This means that the scala.collection.mutable.Map type this blog article. with any scala.Seq (or just Seq) usage in their code: The simplest workaround is to ask your users to call .toSeq on the result which will return an immutable Seq, from older Scala versions. in scope. the last element of this iterable collection$ if it is nonempty, None if it is empty. Scala has Map and map: Map denotes one of the traits for "a map from keys of type A to values of type B" (AKA a hash map), map is a method on collections, including Map, which "builds a new collection by applying a function to all elements of this map".
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