The pipe in F# is slightly different in that most of the time it has no intermediate lambdas and is compiled in a more performant form

I believe the point made in the discussion is that the F# proposal leads to intermediate lambda if the function does not have the right arity. JS also don't do HM so that point is moot.

The people supporting the Hack proposal made the point that their expressions do not desugar to lambda and has no runtime cost, no idea how it works though.