Hi. I have a data type
data Ok_Err s a = Ok s a
and a case expression
case ok_err' of
~(Ok s' a) -> ...
which involved in a loop (i.e. the ... contains a tail call back to the
function containing the case expression).
This takes a lot of space. Specifically the space complexity seems
proportional to the number of loop iterations. Now if
I change the case expression to
let ~(Ok s' a) = ok_err' in ...
then the space requirements become constant and small.
So what's going on? The Haskell standard says that the dynamic sematics
is the same in both cases.
I don't want to use the let, because, really I'd like to exend the
data type to be a sum and the case expression to make a decision. What
I really want is a state monad that supports emergency stops. The case
expression is in the implementation of >>=.
BTW I am using NHC 1.3.
Cheers,
Theo Norvell
----------------------------
Dr. Theodore Norvell [EMAIL PROTECTED]
Electrical and Computer Engineering http://www.engr.mun.ca/~theo
Engineering and Applied Science Phone: (709) 737-8962
Memorial University of Newfoundland Fax: (709) 737-4042
St. John's, NF, Canada, A1B 3X5
