Nim does this, and the whitespace is significant[0][1]:

    echo $foo
    # is parsed as
    echo($foo)

[..]

    echo(1, 2) # pass 1 and 2 to echo
    echo (1, 2) # pass the tuple (1, 2) to echo

[..]

    proc optarg(x: int, y: int = 0): int = x + y
    proc singlearg(x: int): int = 20*x
    
    echo optarg 1, " ", singlearg 2 # prints "1 40"
    
    let fail = optarg 1, optarg 8 # Wrong. Too many arguments for a command call
    let x = optarg(1, optarg 8) # traditional procedure call with 2 arguments
    let y = 1.optarg optarg 8 # same thing as above, w/o the parenthesis
    assert x == y

[0]: https://nim-lang.org/docs/manual.html#syntax-precedence

[1]: https://nim-lang.org/docs/manual.html#procedures-command-inv...