(* Problem 1 *)
let times x y = ...

(* Problem 2 *)
let unfold lst = ...

(* Problem 3 *)
let nonempty_print str = ...

(* Problem 4 *)
let isnull lst = ...

(* Problem 5 *)
let multiply ...

(* Problem 6 *)
let apply f x y = ...

(* Problem 7 *)
let partiallyApply ...

(* Problem 8 *)
let app3 f x y z = ...

(* Problem 9 - Extra Credit *)
let permuteArgs f perm = ...