Thank you all on comments. I have studied referenced sources and now I will upgrade my initial comment in context of mentioned mutative update. I find now that first question that need answer is what is the definition of stream and how pipeline of operations relate to stream.
Method 'map' implies existence of materialized in/out streams. Example is linear queue. This goes with definition on https://en.m.wikipedia.org/wiki/Map_(higher-order_function) using list as map source and output. Same I find in Haskell and Lisp usage of map or mapcar function. Name of map function is indisputable as defined in wiki resources. But is usage of that map function justified in java streams ? With java streams when implementation use operation fusion on pipeline of operations there is no intermediary queue between operations. https://www.ibm.com/developerworks/java/library/j-java-streams-1-brian-goetz/index.html?ca=drs- chapter 'Stream versus collections', about fusion. This is implementation specific ("how" to do it) In common usage word stream represent current of elements. Stream exist if there is at least one moving element. Without moving element there is no stream. Stream have no state. Stream is agnostic on: 1) element type; 2) source state; 3) target state. This is how I see elements going through pipeline of operations when I build sequence of operations ("what" to do with an element in transition). Elements are emitted one by one from backed source collection by stream() operation (stream source), going through pipeline composed of filter() and map() operations, intermediate operations like sorted() (ending one stream and emitting another) and ending with the sink (collect(), count()...). Map method effectively replaces element with computed one, stream doesn't care and source collection is not affected. From this definition of stream goes that operations are on the element, not on a stream (or collection with state). This goes with my stand that word replace(With) would be appropriate name for method, not map. If written description of stream reflect streams library build up than usage of word map for method in question is not justified here. Article https://www.ibm.com/developerworks/java/library/j-java-streams-1-brian-goetz/index.html?ca=drs- describe java streams library. It states that "Streams provide no storage for the elements..." but in comment @Goetz said that 'replace' implies mutative update. Am I missing something? I will appreciate any comments. Best regards, Krunoslav Magazin
