I believe it has to do with features like subtyping and method overloading which...

anaphor on Sept 28, 2013 | parent | context | favorite | on: Why we're supporting Typed Clojure

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