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Yes.. and no. There is a memoization decorator, called CachedFunction (or cached_function), and it can be applied easily:

sage: @CachedFunction
....: def f(x):
....:         print 'slow call..'
....:     sleep(5)
....:     return x**2
....: 
sage: f(10)
slow call..
100
sage: f(10)
100

(Or, equally, g = cached_function(f) or h = CachedFunction(f). I

Unfortunately you can still blow the recursion stack:

sage: @CachedFunction
....: def r(x):
....:         return 1 if x<= 1 else 1+r(x-1)
....:  
sage: r(20)
20
sage: r(2000)
[...]
RuntimeError: maximum recursion depth exceeded while calling a Python object

Unfortunately CPython doesn't do tail-recursion optimization, so writing recursive functions isn't as natural. [If you're interested, there are [some ways around this](http://groups.google.com/group/sage-flame/browse_thread/thread/845077dcd78c4f32?pli=1) but I wouldn't recommend them for production use..]

Yes.. and no. There is a memoization decorator, called CachedFunction (or cached_function), and it can be applied easily:

sage: @CachedFunction
....: def f(x):
....:         print 'slow call..'
....:     sleep(5)
....:     return x**2
....: 
sage: f(10)
slow call..
100
sage: f(10)
100

(Or, equally, g = cached_function(f) or h = CachedFunction(f). I

Unfortunately you can still blow the recursion stack:

sage: @CachedFunction
....: def r(x):
....:         return 1 if x<= 1 else 1+r(x-1)
....:  
sage: r(20)
20
sage: r(2000)
[...]
RuntimeError: maximum recursion depth exceeded while calling a Python object

Unfortunately CPython doesn't do tail-recursion optimization, so writing recursive functions isn't as natural. [If If you're interested, there are [some some ways around this](http://groups.google.com/group/sage-flame/browse_thread/thread/845077dcd78c4f32?pli=1) this but I wouldn't recommend them for production use..]use..

Yes.. and no. There is a memoization decorator, called CachedFunction (or cached_function), and it can be applied easily:

sage: @CachedFunction
....: def f(x):
....:         print 'slow call..'
....:     sleep(5)
....:     return x**2
....: 
sage: f(10)
slow call..
100
sage: f(10)
100

(Or, equally, g = cached_function(f) or h = CachedFunction(f). I.)

Unfortunately you can still blow the recursion stack:

sage: @CachedFunction
....: def r(x):
....:         return 1 if x<= 1 else 1+r(x-1)
....:  
sage: r(20)
20
sage: r(2000)
[...]
RuntimeError: maximum recursion depth exceeded while calling a Python object

Unfortunately CPython doesn't do tail-recursion optimization, so writing recursive functions isn't as natural. If you're interested, there are some ways around this but I wouldn't recommend them for production use..

Yes.. and no. There is a memoization decorator, called CachedFunction (or cached_function), and it can be applied easily:

sage: @CachedFunction
....: def f(x):
....:         print 'slow call..'
....:     sleep(5)
....:     return x**2
....: 
sage: f(10)
slow call..
100
sage: f(10)
100

(Or, equally, g = cached_function(f) or h = CachedFunction(f).)

Unfortunately you can still blow the recursion stack:

sage: @CachedFunction
....: def r(x):
....:         return 1 if x<= 1 else 1+r(x-1)
....:  
sage: r(20)
20
sage: r(2000)
[...]
RuntimeError: maximum recursion depth exceeded while calling a Python object

Unfortunately CPython doesn't do tail-recursion optimization, so writing recursive functions isn't as natural. If you're interested, there are some ways around this but I wouldn't recommend them for production use..