[CLJ-140] Single :tag for type hints conflates value's type with type of return value from an invoke

Tue, 24 Aug 2010 03:51:00 -0500

The value of a Var can be operated on directly, or, if it is a fn, it can be invoked and the resulting value operated on. :tag metadata on a Var is used to provide a type hint to the compiler to avoid reflection. Having a single metadata key for this two distinct uses makes it possible (even easy, if unlikely) to create a situation where type-hinting the value causes a ClassCastException on an operation on the invocation return value, or the reverse. The only obvious solution is two use different keys for the two uses.

Clojure JIRA

[CLJ-140] Single :tag for type hints conflates value's type with type of return value from an invoke