Greval is a simple toy scripting language in the making. So far it can handle C-like expressions and can export C++ functions to the scripting side.
$ greval-eval 5 + 5
Syntax Tree: (+ 5 5)
EvalVisitor: integer:10
$ greval-eval "sqrt(2)"
Syntax Tree: (sqrt 2)
EvalVisitor: real:1.414214