Are there type signatures which Haskell can't verify?

Question

This paper establishes that type inference (called \"typability\" in the paper) in System F is undecidable. What I\'ve never heard mentioned elsewhere is the second result of th

Answer 1

Here is an example for a type level implementation of the SKI calculus in Scala: http://michid.wordpress.com/2010/01/29/scala-type-level-encoding-of-the-ski-calculus/

The last example shows an unbounded iteration. If you do the same in Haskell (and I'm pretty sure you can), you have an example for an "untypeable expression".