Consider the implementation of a properly lazy "const" function in Haskell:
const x _ = x
http://apocalisp.wordpress.com/2010/04/21/a-proper-constant-...
Not sure about Coq, but Agda is Turing Complete (you just need to turn off termination checks) and Epigram also supports general recursion as well as structural recursion with total functions.
I was trying to point that the "more powerful" criteria is pretty subjective.
The OP said "more powerful than the alternatives", that usually means "runs in the JVM"... and AFAIK, Jaskell or CAL are far from mature.
Consider the implementation of a properly lazy "const" function in Haskell:
And in Scala:http://apocalisp.wordpress.com/2010/04/21/a-proper-constant-...
Not sure about Coq, but Agda is Turing Complete (you just need to turn off termination checks) and Epigram also supports general recursion as well as structural recursion with total functions.