Clojure is a great language, but there really is a difference between functional and "pretty" functional; e.g. as in, I know 100% sure that this function has no side-effects.
Static typing can do a lot of good, but the stricter semantics of Haskell also goes a long way into writing code with fewer bugs.
Nobody can agree on the definition of a functional language. AFAIK, so-called "functional" languages like F# or O-Camel allow arbitrary side effects, unlike Haskell.
Any function changes the state of your machine, and you have to pretend your computer doesn't have memory or registers in order for this pure function side effect free stuff to make sense. When you said "know 100%" my ability to accept abstractions like that turned off.
Haskell has support for side-effects. It's just able to state the property that something is a 100% pure function, and also makes it very easy to write such code a lot of the time.
I disagree. That may be true in Haskell because it's static and the compiler finds a lot of problems.
This isn't true for all functional languages though. I REALLY want a debugger in Clojure code and it's pretty functional*.