I don't think the methods mentioned in the haskell wiki are quite equivelent to the python decorator, as they require you to modify the data structure itself to

I don't think the methods mentioned in the haskell wiki are quite equivelent to the python decorator, as they require you to modify the data structure itself to support memoization. It should be possible to use UnsafePerformIO to create a generic function memoize function (at least for inputs that implelemt Eq or Ord), but that is almost definantly overkill and asking for space leaks.