representation

I know that methods __repr__ and __str__ exist to give a formal and informal representation of class instances. But does an equivalent exist for class objects too, so that when the class object is printed, a nice representation of it could be shown? >>> class Foo: ... def __str__(self): ... return "instance of class Foo" ... >>> foo = Foo() >>> print foo instance of class Foo >>> print Foo __main__.Foo unutbu When you call print(foo) , foo 's __str__ method is called. __str__ is found in the class of foo , which is Foo . Similarly, when you call print(Foo) , Foo 's __str__ method is called. _

UPDATE The main questions remain the ones under the example, but I guess it boils down to : **If you have a type where 99% of the values could be represented in one fast, powerfull type, and only 1% in a very heavy type, (say int vs. BigInteger) How to represent it?? ** A school we learned a lot about internal representations, but never how to change it at runtime. I mean : suppose you have a class representing a decimal, but you use an integer to represent it internal, until you actually need a bigger value than the integer, and only than change representation... I never thought of this

What is a good way to represent finite automaton in Haskell? How would the data type of it look like? In our college, automata were defined as a 5-tuple (Q, X, delta, q_0, F) where Q is the set of automaton's states, X is the alphabet (is this part even necessery), delta is the transition function taking 2-tuple from (Q,X) and returning state/-s (in non-deterministic version) and F is the set of accepting/end states. Most importantly, I'm not sure what type delta should have... There are two basic options: An explicit function delta :: Q -> X -> Q (or [Q] as appropriate) as Sven Hager suggests

Just asked by my 5 year old kid: what is the biggest number in the computer? We are not talking about max number for a specific data types, but the biggest number that a computer can represent. Infinity is not allowed. UPDATE my kid always wants to print as well, so lets say the computer needs to print this number and the kid to know that its a big number. Of course, in practice we won't print because theres not enough trees. This question is actually a very interesting one which mathematicians have devoted a fair bit of thought to. You can read about it in this article , which is a

I've been looking at Haskell and I'd quite like to write a compiler (as a learning exercise) in it, since a lot of it's innate features can be readily applied to a compiler (particularly a recursive decent compiler). What I can't quite get my head around is how to represent a language's grammar in a Haskell-ian way. My first thought was to use recursive data type definitions, but I can't see how I use them to match against keywords in the language ("if") for example. Thoughts and suggestions greatly appreciated, Pete A recursive data type is fine for this. For example, given the language: expr