Unityped vs multityped

Performance Warning: Matrix values are arrays, as exported by math/array. The same performance warning applies: operations are currently 25-50 times slower in untyped Racket than in Typed Racket, due to the overhead of checking higher-order contracts. We are working on it.
http://docs.racket-lang.org/math/matrices.html

Still not convinced that unityped languages suck ass?

>>39
Types are metainformation used to formally prove the absence of certain errors without running the program.
Having type tags at runtime is just useless overhead.
Having type tags at runtime means that your language and/or compiler is too shitty to figure the types out without running the program.
For the rest, read your damn TAPL. I'm sick of explaining all of this.

any function compiled to manually dispatch over the tags of a tagged union at run-time must be recompiled if a new type is added (something very undesirable)
This "very undesirable" thing means that you can add functions over that type without recompiling. The situation is entirely dual and symmetric: either you can add types without recompiling but not functions, or the other way around. The first case is the case of OOP (easily add types), the second is the case of FP (easily add functions).