[danellis]

It seemed like a reasonable idea until I saw the syntax.

    Object.keys(envars)
      .map(envar => `${envar}=${envars[envar]}`)
      .join(' ')
      |> `$ ${%}`
      |> chalk.dim(%, 'node', args.join(' '))
      |> console.log(%);

Okay, from the other comments, I gather this is like Hack. Does any other language use a pipe operator for non-unary functions? Does the `%` syntax apply more generally? What is the type of `foo(%, 1, 2)`? One would expect it to be the same as `placeholder => foo(placeholder, 1, 2)`, but is it?

For example, in Scala, if I have `foo(Int, Int, Int): Int`, then `foo(_, 1, 2)` has type `Int => Int`. That's true anywhere, but in the JavaScript proposal we seem to have a syntax that only applies in a special case.