CODEWITHSUNDEEP
ooprecursionmethodsocaml
Mat Kelly
Mat Kelly

Reputation: 2366

Recursive functions within OCaml objects

I am trying to figure out recursion for OCaml in the context of an object's method. I have tried the following code but can't seem to get it to compile.

class foo =
object (self)
 method loopTest =
  let rec doIt x =
   Printf.printf "%d\n" x;
   if x>1 then doIt (x+1)
end;;

How do I create a recursive function of this sort within a method?

Revised code:

class foo =
object (self)
 method loopTest =
  let rec doIt x =
   Printf.printf "%d\n" x;
   if x<10 then doIt (x+1) in doIt 0
end;;

Upvotes: 3

Views: 1892

Answers (2)

Kurt Schelfthout
Kurt Schelfthout

Reputation: 8980

You still need to call doIt in your loopTest method. let just defines doIt, just like method just defines a method, and does not call it. The compiler detects this because it doesn't know what to return from loopTest (like a method that does not have return type void, but has no implementation in C# or Java).

Also, you're in for an infinite loop with this code, maybe if x>1 then doIt (x-1) followed by doIt 100 is a better idea.

Upvotes: 4

Logan Capaldo
Logan Capaldo

Reputation: 40336

My OCaml is rusty, but I don't think let evaluates to what it bound. If you want testLoop to call doIt, tack on a in doIt or similar.

Upvotes: 2

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