You made the same mistake :)<br> <br>
removeDuplTuples x:xs = nub(if ((snd x,fst x) `elem` xs) then
(removeDuplTuples xs) else ([x] ++ removeDuplTuples xs))<br><br>Should be:<br><br>
removeDuplTuples (x:xs) = nub(if ((snd x,fst x) `elem` xs) then
(removeDuplTuples xs) else ([x] ++ removeDuplTuples xs))<br><br><br>You need to put parenthesis around x:xs. <br><br>Greets,<br><br>Edgar<br><br><div class="gmail_quote">On Tue, Sep 28, 2010 at 11:57 AM, Martin Tomko <span dir="ltr"><<a href="mailto:martin.tomko@geo.uzh.ch">martin.tomko@geo.uzh.ch</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000">
Hi Edgar,<br>
thanks for the help. I wanted to first test with nub, but I still
cannot get it to work. I cannot see any missing parenthesis, but I
retyped it this way to check:<div class="im"><br>
<br>
removeDuplTuples :: (Eq a) =>[(a,a)] -> [(a,a)]<br>
removeDuplTuples [] = []<br>
removeDuplTuples [b] = [b]<br></div>
removeDuplTuples x:xs = nub(if ((snd x,fst x) `elem` xs) then
(removeDuplTuples xs) else ([x] ++ removeDuplTuples xs))<br>
<br>
still the same error<br>
<br>
What am I missing?<br><font color="#888888">
Martin</font><div><div></div><div class="h5"><br>
<br>
On 9/28/2010 11:45 AM, edgar klerks wrote:
<blockquote type="cite">>You forgot the parenthesis. Parse error in pattern
usually means a type in the input of one of your functions. Nub needs
>elements that can be equal.<br>
<br>
type has to be typo. <br>
<div class="gmail_quote">On Tue, Sep 28, 2010 at 11:44 AM, edgar
klerks <span dir="ltr"><<a href="mailto:edgar.klerks@gmail.com" target="_blank">edgar.klerks@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi
Martin, <br>
<br>
You have some typos:<br>
<br>
import Data.List<br>
removeDuplTuples :: (Eq a) => [(a,a)] -> [(a,a)]
<div><br>
removeDuplTuples [] = []<br>
removeDuplTuples [b] =
[b]
-- using the syntactic sugar for single element in list<br>
removeDuplTuples (x:xs) = nub (if elem (snd x,fst x) xs then
removeDuplTuples xs else [x] ++ removeDuplTuples xs)<br>
</div>
--------<br>
You forgot the parenthesis. Parse error in pattern usually means a type
in the input of one of your functions. Nub needs elements that can be
equal.<br>
<br>
Nub is quitte inefficient, if your elements can be ordered, there is a
more efficient version. It is something like: <br>
<br>
fmap head.group.sort $ [1,1,1,1,4,4,5,6,6,7,8,9]<br>
[1,4,5,6,7,8,9]<br>
<br>
But I haven't test it thoroughly. <br>
<br>
Greets,<br>
<font color="#888888"><br>
Edgar <br>
</font>
<div>
<div><br>
<div class="gmail_quote">On Tue, Sep 28, 2010 at 11:33 AM, Martin
Tomko <span dir="ltr"><<a href="mailto:martin.tomko@geo.uzh.ch" target="_blank">martin.tomko@geo.uzh.ch</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi
all,<br>
I apologize for spamming this forum so frequently, but there is noone I
can turn to around here...<br>
I have a list of (a,a) tuples, and am trying something like nub, but
also matching for symmetrical tuples. I implemented it using the
template from delete from Prelude. Seems like my typse signature has
some troubles (Paarse error in pattern) but I am not sure where the
problem is.<br>
<br>
removeDuplTuples :: [(a,a)] -> [(a,a)]<br>
removeDuplTuples [] = []<br>
removeDuplTuples [b] = [b]
-- using the syntactic sugar for single element in list<br>
removeDuplTuples x:xs = nub (if elem (snd x,fst x) xs then
removeDuplTuples xs else [x] ++ removeDuplTuples xs)<br>
<br>
I assume the problem lies in elem (snd x,fst x) xs but I am not sure
how to rewrite it.<br>
<br>
Thanks for all help,<br>
Martin<br>
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</div></div></div>
</blockquote></div><br>