I really do not understand why I keep seeing static typing advocates recite this "dynamic languages only have one type!" line like it's some kind of profound insight.
Yes, obviously you can view a dynamic language as having only a "top" type. That's largely the point.
As for the post, I'm assuming it was written as some kind of tongue-in-cheek reverse troll, as I'd really like to believe Robert Harper doesn't drip condescension like that without being fully aware of it.
IIRC there are several posts on that blog just obsessing over how awesome static typing is. On the other hand there are probably more people who are ignorant about the value of static typing than that of dynamic typing.
Every time this is brought up I always imagine writing a complete library to support a super-type for some static language that has tagged unions and operator overloading such that the user will rarely if ever need to inspect the type tag. And the more I think about this the more I realize you'd get gradual typing on primitives for free.
Yes, obviously you can view a dynamic language as having only a "top" type. That's largely the point.
As for the post, I'm assuming it was written as some kind of tongue-in-cheek reverse troll, as I'd really like to believe Robert Harper doesn't drip condescension like that without being fully aware of it.