Reported by rosejn, Mar 19, 2009
user=> (if-let [foo (+ 1 2)] foo + 1 foo)
java.lang.IllegalArgumentException: if-let requires a vector for its
The error reports that if-let requires a vector for its binding, but the
problem here has nothing to do with the binding being a vector. A paren
was forgotten before the '+', so the number of arguments is incorrect for
the if form.