<div dir="ltr">Have you read <a href="http://ics.p.lodz.pl/~stolarek/_media/pl:research:stolarek_understanding_basic_haskell_error_messages.pdf">this</a>? I found it fascinating, helpful, and (perhaps unlike most papers out there on Haskell) not at all difficult to read quickly.</div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Nov 9, 2014 at 5:11 AM, Roelof Wobben <span dir="ltr"><<a href="mailto:r.wobben@home.nl" target="_blank">r.wobben@home.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Thanks, <br>
<br>
Now when I run it, I see a error message that main is missing.<br>
and I cannot find in theIlearnyouahaskell how to solve this.<br>
<br>
Roelof<br>
<br>
<br>
<br>
<br>
May Khaw schreef op 9-11-2014 11:17:<br>
</div><div><div class="h5">
<blockquote type="cite">The first one means that you gave a type signature for
a function you did not define. <br>
<br>
The second one means that there are 2 last2 type signature, but
you can only have one. <br>
<br>
What you want is something like :<br>
last2 :: [a] - > a<br>
last2 list = (put your function here) <br>
<br>
<div class="gmail_quote">On Sun, 9 Nov 2014 21:02 Roelof Wobben
<<a href="mailto:r.wobben@home.nl" target="_blank">r.wobben@home.nl</a>>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Thanks, <br>
<br>
I changed it to this : <br>
<br>
last2::[a]-> a<br>
last2::last[a]<br>
<br>
but now I see these error messages: <br>
<br>
<div>
<div>src/Main.hs@1:1-1:6<span> The type signature for</span><span>last2</span><span>
lacks an accompanying binding</span></div>
</div>
<div>
<div>src/Main.hs@2:1-2:6<span> Duplicate type signatures
for</span><span> last2</span><span> <br>
at
/home/app/isolation-runner-work/projects/75679/session.207/src/src/Main.hs:1:1-5
<br>
/home/app/isolation-runner-work/projects/75679/session.207/src/src/Main.hs:2:1-5</span>
src/Main.hs@2:1-2:6 </div>
</div>
<div>
<div><span>The type signature for</span><span> last2</span><span>
lacks an accompanying binding</span></div>
</div>
<br>
<br>
<br>
akash g schreef op 9-11-2014 10:48:<br>
</div>
</div>
<div text="#000000" bgcolor="#FFFFFF">
<blockquote type="cite">
<div dir="ltr">The naming convention for variables and
functions is that they should start with a lower case
letter. Types have capitalized names.<br>
<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Sun, Nov 9, 2014 at 3:12 PM,
Roelof Wobben <span dir="ltr"><<a href="mailto:r.wobben@home.nl" target="_blank">r.wobben@home.nl</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"> <br>
<div><br>
<br>
<table border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<th valign="BASELINE" align="RIGHT" nowrap><br>
</th>
<td><br>
</td>
</tr>
<tr>
<th valign="BASELINE" align="RIGHT" nowrap><br>
</th>
<td><br>
</td>
</tr>
<tr>
<th valign="BASELINE" align="RIGHT" nowrap><br>
</th>
<td><br>
</td>
</tr>
<tr>
<th valign="BASELINE" align="RIGHT" nowrap><br>
</th>
<td><br>
</td>
</tr>
</tbody>
</table>
<br>
<br>
<pre>Hello,
I try to solve the 99 haskell problems on several ways.
But my first try which looks like this :
Last2::[a]-> a
Last2:: last[list]
gives the following error message :
src/Main.hs@1:1-1:6
Invalid type signature: Last2 :: [a] -> a Should be of form <variable>
:: <type>
What am trying to do is say the input is a list which can be of integers
or chars so everything is the output can then also be of type everything.
Roelof
</pre>
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