What does ?~> meaning in the scala programming language?

Question

I met with the below statements in a scala code

val stage = stage1 ?~> stage2 ?~> stage3 ~> stage4

Can anyone please explain the meaning of the ?~> and how these statements will be evaluated.

Where did you see this code? Akka by any chance? I am not sure this is in the standard library — sinanspd
– sinanspd, Commented Jun 6, 2022 at 5:38

Tim · Accepted Answer · 2022-06-06 05:59:04Z

3

An infix operation a op b is compiler shorthand for a.op(b). So that code is directly equivalent to

((stage1.?~>(stage2)).?~>(stage3)).~>(stage4)

which is evaluated like this:

val t1 = stage1.?~>(stage2)
val t2 = t1.?~>(stage3)
val result = t2.~>(stage4)

?~> is a method of the object stage1 that returns an object that has a ?~> method that returns an object with a ~> method.

What it actually does depends on what library you are using and the type of the stage objects.

answered Jun 6, 2022 at 5:59

Tim

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