On Jul 13, 2010, at 9:00 PM, Christopher Done wrote:
On 13 July 2010 10:58, vadali <shlomivak...@gmail.com> wrote:\
i want to define a function which takes as a parameter a list which
can
contain other lists, eg. [1,[2,3],[4,[5,6]]]
What would the type of a list like that be?
What you _can_ do is
data List_Or t = Item t | List [List_Or t]
deriving (Eq, Ord, Show)
and have a "list" like
ell :: List_Or Int
ell = List [Item 1, List [Item 2, Item 3], List [Item 4,
List [Item 5, Item 6]]]
how would i define a function that can iterate through the items so
(in this
example)
iter1 = 1
iter2 = [2,3]
iter3 = [4,[5,6]]
Then you can write functions like
iter n (List x) = head (drop (n-1) x)
with examples
*Main> iter 1 ell
Item 1
*Main> iter 2 ell
List [Item 2,Item 3]
*Main> iter 3 ell
List [Item 4,List [Item 5,Item 6]]
( can i do that without using the Tree data type? )
This basically _is_ a tree data type, even if not THE Tree
data type. That's because nested lists are trees.
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