How to use <> for Seq

[oharboe]

Is there a way to use <> for Seq?

So I have a local variable Seq[Foo] of modules, and a val bar=Vec(n, new FooBundlke()) in my io and I want to hook the Foos to the io...

  foos.map(_.io.foo) <> io.foo

[oharboe]

@hovind FYI

[jackkoenig]

We should add this to Chisel itself (or better yet, implement Connectable[Seq[T <: Data]], but it's pretty easy to add an extension method:

object Whatever {
  implicit class SeqExtensions[T <: Data](xs: Seq[T]) {
    def :<>=(rhs: Seq[T]): Unit =
      xs.zip(rhs).foreach { case (l, r) => l :<>= r }
  }
}

Then you just make sure to import SeqExtensions into your lexical scope:

import Whatever._
// or
import Whatever.SeqExtensions

Then you can use the extension operator:

foo.map(_.io.foo) :<>= io.foo

I am using :<>= instead of <> just because it has better behavior but you can of course do the same thing with <>.

[oharboe]

Good to know!

Regardless of what happens, there are no plans to change the behavior of :<>=, so it is "safe" to use now?

Can I create a slide for our next planning meeting?

TL;DR Use :<>=

:-)

[jackkoenig]

:<>= is safe to use 🙂. Any changes would be API extensions, not deprecation or modifications.

[mwachs5]

We should deprecate the behavior we don't like (lack of Scala type safety and implicit truncation),

The other major difference is the directionality inference of <>. Need to deprecate that one too.

[jackkoenig]

With more thought and discussion, I think we should just deprecate <> altogether.

[oharboe]

With more thought and discussion, I think we should just deprecate <> altogether.

What tipped the scales?

Precedence rules?

[mwachs5]

I would encourage us if we add this to chisel to add a check that the sequences are the same length

[oharboe]

Example of how to do this without waiting for a Chisel upgrade: https://scastie.scala-lang.org/f8sVrCjcRuqOCARbgkx28w