As described in the link you posted. You can use Y-combinator. Here is example:
scala> def fix[A,B](f: (A=>B)=>(A=>B)): A=>B = f(fix(f))(_) fix: [A,B](f: ((A) => B) => (A) => B)(A) => B scala> val fact = fix[Int,Int](f => a => if(a<=0) 1 else f(a-1) * a) fact: (Int) => Int = <function1> scala> fact(12) res0: Int = 479001600
Note it doesn’t work with big numbers.
Be careful with tail call optimization.