It would make the function name stand out from the parameters. Again, to pick one unintuitive abbrevation, just because it's a 3-letter one like let, it's just not serious! Make all be 3:
type -> typ
switch -> swi
if -> iff
else -> els
in -> inn
downto -> dow
module -> mod
Call you language 3-letter reason. You see how it ridiculous it gets? You can't make all keywords be 3-letter and if people care about alignment, they can further align, but most don't care as much as you think!