At 12:50 AM +0800 2005/5/23, wenduan wrote:
hi,
Anybody could please tell me that in the following two expressions
what value does the [] take?
foldl (/) 3 []
foldr (/) 3 []
when both of them are evaluated I got 3.0,but I thought I could get
nothing out of there,cause its an empty list,does Haskell assume any
default value for a empty list?
A quick check of the equations that define foldl and foldr (see
Prelude.hs) shows that when either of them has an empty list for its
third argument, it returns its second argument.
Regards,
--Ham
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Hamilton Richards, PhD Department of Computer Sciences
Senior Lecturer The University of Texas at Austin
512-471-9525 1 University Station C0500
Taylor Hall 5.138 Austin, Texas 78712-0233
[EMAIL PROTECTED] [EMAIL PROTECTED]
http://www.cs.utexas.edu/users/ham/richards
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