[Haskell-cafe] Re: Large data structures

Alex Queiroz wrote:

On 12/11/06, Stefan O'Rear wrote:

...

No. Haskell's lists are linked lists, enlarge creates a single new link without modifying (and copying) the original. Thanks. Is there a way to mimic this behaviour with my own code?

It is the default for any data structure you define. Data is by default represented internally as a pointer to the actual value. Otherwise recursive structures (see below for an example) would not be easily possible. And since no part of the data structure is 'mutable', different instances can share (memory-wise) as much of their structure as the implementation is able to find. BTW apart from the special syntax (like [a,b,c]) there is nothing special about lists. E.g. with this data type definition data List a = Nil | Cons a (List a) (List a) is completely equivalent to [a]. HTH Ben PS: Please try to include exactly the relevant context in replies, no more, no less. Your original question (stripped down to the body of the text) would have been relevant, here, but neither 'Hello', nor 'Cheers' are worth quoting.