bash - Why does Scala use a reversed shebang (!#) instead of just setting interpreter to scala

Question

The scala documentation shows that the way to create a scala script is like this:

#!/bin/sh
exec scala "$0" "$@"
!#
/* Script here */

I know that this executes scala with the name of the script file and the arguments passed to it, and that the scala command apparently knows to read a file that starts like this and ignore everything up to the reversed shebang !#

My question is: is there any reason why I should use this (rather verbose) format for a scala script, rather than just:

#!/bin/env scala
/* Script here */

This, as far a I can tell from a quick test, does exactly the same thing, but is less verbose.

Answer 1

How old is the documentation? Usually, this sort of thing (often referred to as 'the exec hack') was recommended before /bin/env was common, and this was the best way to get the functionality. Note that /usr/bin/env is more common than /bin/env, and ought to be used instead.