Using a predicate in the filter function of "< limit and mod 2 == 0" does not work as the fibs sequence is evaluated even after the terms in the sequence become greater than the limit (all it means is that every term above the limit is filtered out). Replacing the limit check with take-while would fix this.
The third solution is also broken, it works fine for small values of n but enter a large number such as is given in the problem and you quickly run out of stack. Replacing the recursive call with recur will enable tail-call optimisation and give your stack a lot more breathing room.
I recommend the clojure-euler wiki for more reliable examples of good clojure code :)
Ha thanks for your comments spuz. Not sure what happened on #2 that I ended up posting broken code. For number #3, I don't think recur will work without changing the algorithm a bit. There are 2 recursive calls depending on the conditional, and recur needs to be last for it to compile. Also in my defense it works on my machine ;)
So, yes its a learning process. I'm updating the post. Thanks again for your comments.
I tried your solution to #3 on my old windows laptop and trying to find the prime factors for 600851475143 gave a stack overflow. However, replacing the recursive calls with recur produced the correct result. I think this is because only one of the two branches that recurse is ever executed so tail-call optimisation is still possible in this case. If it was called twice (as in some implementations of the Fibonacci sequence) I'm guessing it would fail.
The second solution will run indefinitely:
Using a predicate in the filter function of "< limit and mod 2 == 0" does not work as the fibs sequence is evaluated even after the terms in the sequence become greater than the limit (all it means is that every term above the limit is filtered out). Replacing the limit check with take-while would fix this.The third solution is also broken, it works fine for small values of n but enter a large number such as is given in the problem and you quickly run out of stack. Replacing the recursive call with recur will enable tail-call optimisation and give your stack a lot more breathing room.
I recommend the clojure-euler wiki for more reliable examples of good clojure code :)