(Moved to haskell-cafe) JU> General question to the list: JU> (Q) Are there any data structures in Haskell similar to C++/STL JU> vectors or C# generic Lists (i.e. strongly typed ArrayLists, e.g. JU> List<int>)? These data structures grow automatically as you add JU> elements to them (but in large chunks, not one node at a time). This JU> data structure (if it exists in Haskell) would run inside a monad (ST JU> and/or IO) and it would automaticly resize when needed, but would be JU> more or less like a mutable array except you can add new elements to JU> the end of it without reallocating an entire array of n+1 elements... i tried to implement this today :) but there is one problem:
if i have (l,u) - array bounds of type Ix, and i - offending index of the same type, how can i compute new bounds of array so that it will grow in large chunks? there is no such computation operations for Ix type and that is logical - if this array is really a matrix then it's hard to use the same rules of extending it as for vectors
Hmmm, that is a problem, especially as you said, for enum types that are bounded above. I guess you can't make it grow more than the min and max. For the most part, this dynamic array would only be useful for arrays with indices isomorphic to the natural numbers.
such computation as (u-l)*2+l is great for integral indexes, but not for general case. now i plan to use this strategy for all enum types and just "grow to minimal and maximal indexes actually used" for other index types
Perhaps the function to build these DynamicArrays could take a Maybe parameter telling the maximum possible range (for bounded enums) or Nothing if the array is allowed to grow indefinitely. Or an Either parameter where Left (a,a) tells the max range and Right (a,a) -> (a,a) which tells how the range should grow on a resize. Or just the range resize function :: (a,a) -> (a,a) telling how to grow on a resize, i.e. for enums function = id. Something like that. Jared.