Clojure to Objective-C (built with Haskell)
github.com
github.com
However, it seems like an odd choice to write this in Haskell. Why eschew ClojureScript?
The ClojureScript compiler has a (reasonably) decoupled analyzer and reuses the reader from JVM Clojure. The core lib is already extremely robust and performant; it's becoming more so every day. That's a lot of code to ignore.
Granted, there are still some JavaScript specific bits glued in there, but you could fork and not care about contributing decoupling-patches to ClojureScript proper. The team would still still appreciate knowledge of what bits you needed to change and what challenges you faced. There are ongoing efforts for a Lua backend and self-hosting. An LLVM backend with Cocoa support would be a very worthwhile project!