Imperative pipelines (“tap” operators)

[usaoc]

Some languages provide pipeline operators or alike for use with imperative functions/methods:

• Clojure provides doto that works like ->, except that each forms are evaluated and discarded, and the original value is returned. For example, (doto (new java.util.HashMap) (.put "a" 1) (.put "b" 2)) initiates a Java mutable hash table (see the ClojureDocs page).
• In Kotlin, .apply (with receiver) and .also (with argument) are available as extension methods on objects (see Kotlin scope functions).
• (Unfortunately, I couldn’t find a precedent on a .- or |>-like tap operator.)

This operation is also known as “tap” or “tee”. Is this a useful addition to Rhombus?

[samth]

For doto: I think it's more useful to have the underlying API return the mutable object instead of void, which means just regular pipelines work properly.

[mflatt]

FWIW, I experimented early on with having methods of mutable objects return the object, and I found it noisy (because results tend to get printed) and less clear than having Void as a result to highlight imperative behavior.