Today, I reviewed a function I wrote
a few months ago. The function, dropTrailNulls, takes a list of lists
and drops trailing null lists. For instance:
*Main dropTrailNulls [[1],[2,3],[],[]]
[[1],[2,3]]
My original implementation was terrible.
It was recursive, overly bulky, and difficult to
dropTrailNulls list = reverse (dropWhile null (reverse list))
Or more succinctly:
dropTrailNulls = reverse . dropWhile null . reverse
Or, is there a more efficient idiom for addressing these problems?
The bad thing about this definition is that it is tail strict. Consider
On Mar 8, 2006, at 12:08 PM, [EMAIL PROTECTED] wrote:Today, I reviewed a function I wrote a few months ago. The function, dropTrailNulls, takes a list of lists and drops trailing null lists. For instance: *Main dropTrailNulls [[1],[2,3],[],[]] [[1],[2,3]] My original implementation was
[EMAIL PROTECTED] wrote:
Today, I reviewed a function I wrote a few months ago. The function,
dropTrailNulls, takes a list of lists and drops trailing null lists. For
instance:
*Main dropTrailNulls [[1],[2,3],[],[]]
[[1],[2,3]]
dropTrailNulls = foldr dtn []
where
dtn [] [] = []
Hello Jeff,
Wednesday, March 8, 2006, 8:08:57 PM, you wrote:
dropTrailNulls list = reverse (dropWhile null (reverse list))
dropTrailNulls [] = []
dropTrailNulls ([]:xs) = case dropTrailNulls xs of
[] - []
list - []:list
dropTrailNulls (x:xs) = x :
On Wed, 8 Mar 2006 [EMAIL PROTECTED] wrote:
Today, I reviewed a function I wrote a few months ago. The function,
dropTrailNulls, takes a list of lists and drops trailing null lists. For
instance:
*Main dropTrailNulls [[1],[2,3],[],[]]
[[1],[2,3]]
