[moomin]

I'm far from an expert on this, but F# has no requirement for all forms to be explicitly typed, so I'm a bit puzzled as to why this is hard.

[ambrosebs]

Typed Clojure's type system is too rich to avoid top-level annotations. It's a similar situation to Scala.

[anaphor]

I believe it has to do with features like subtyping and method overloading which cause havok for global type inference. Found a paper here: http://ropas.snu.ac.kr/lib/dock/HoMi1995.ps