Calls to labeled functions and line continuation

[cspiel]

Function calls to functions with labeled parameters cannot be
spread out over several lines.

Calls to un-labeled functions work ok as the following example demostrates.

iota(first, last, stride) =
        iter(a, x) =
                if $(gt $x, $(last))
                        return $a
                else
                        return $(iter $(array $a, $x), $(int $(add $x, $(stride))))
        empty[] =
        iter($(empty), $(first))

xs = $(iota \
           $(int 1), \
           $(int 10), \
           $(int 2)) # OK to use line continuations here.
printvln($(xs))

Calling labeled_iota on a single line also works, but spreading
out the call over several lines makes omake barf.

labeled_iota(~first, ~last, ~stride) =
        return $(iota $(first), $(last), $(stride))

ys = $(labeled_iota ~stride=$(int 1), ~first=$(int 0), ~last=$(int 4)) # OK: one-liner.
printvln($(ys))

zs = $(labeled_iota \
           ~stride=$(int 1), \
           ~first=$(int 0), \
           ~last=$(int 4)) # Bug: raises error 'keyword argument is required: last'!
printvln($(zs))

My more general wish is open parenthesis working is in many UN*X shells.
This is as long as at least one level of parenthesis is active line continuation
is implied and does not need to be specified via the backslash operator.

I can make that a separate enhancement request if desired.