print <STDOUT> , "Hello"; #runs

<STDOUT> reads from the STDOUT filehandle (which won't do anything useful).

You can't put a comma between the file-handle and the printable content, the syntax is not short for any other syntax.

  print HANDLE expression

is the normal form.

  print expression

is parsed by perl to mean   print LATESTHANDLE expression

where LATESTHANDLE is the last handle given to select() (the default is STDOUT).

-David