Collect filtered stream results into a new List.

Use 'collect as' to materialise a stream into a list:

  positives <- cat items | filter by isPositive | collect as List of Integer

The result is a new List containing all items that passed the pipeline. See Q954, Q1134.

Example

defines module qa.streams.streamcollectas

  defines function

    isPositive() as pure
      -> item as Integer
      <- rtn as Boolean: item > 0

  defines program

    StreamCollectAsDemo()
      stdout <- Stdout()

      items <- [10, -5, 20, -3, 30, -1]

      //Collect filtered results into a list
      positives <- cat items
        | filter by isPositive
        | collect as List of Integer

      stdout.println(`Collected ${$ length positives} items`)
      cat positives > stdout

Other ways to ask this

I need to capture a pipeline's output as a List instead of printing it
In Java I'd use .collect(Collectors.toList()). Write the EK9 equivalent
Given a filtered stream, materialise the results into a List of Integer
Store the output of a stream pipeline in a variable using collect as

Coming from another language?

Java: .collect(Collectors.toList()). Python: list(filter(...)). Rust: .collect::<Vec<_>>(). EK9: | collect as List of T.

Keywords: materialise, result, collect, list, capture, pipeline