<div dir="ltr">I believe, you don't need main at all. Just load your source with ghci and call your functions from there.<br></div><br><div class="gmail_quote">On Tue, May 12, 2015 at 9:48 AM Roelof Wobben <<a href="mailto:r.wobben@home.nl">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 bgcolor="#FFFFFF" text="#000000">
    <div>Thanks <br>
      <br>
      Can I just say Main = <br>
      I will google to look how to make a safeLast.<br>
      <br>
      Roelof<br>
      <br>
      <br>
      <br>
      Alexey Shmalko schreef op 12-5-2015 om 8:46:<br>
    </div></div><div bgcolor="#FFFFFF" text="#000000">
    <blockquote type="cite">
      <div dir="ltr">last' [] = error "last' on empty list"<br>
        <br>
        Otherwise, you should wrap the result in Maybe to make your
        function work as safeLast.
        <div><br>
        </div>
        <div>Oh... GHC's exception seems to say you haven't defined
          `main` in your module.</div>
      </div>
      <br>
      <div class="gmail_quote">On Tue, May 12, 2015 at 9:42 AM 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 bgcolor="#FFFFFF" text="#000000">
            <div>Mike Meyer schreef op 12-5-2015 om 8:39:<br>
            </div>
          </div>
          <div bgcolor="#FFFFFF" text="#000000">
            <blockquote type="cite">
              <p dir="ltr">On May 12, 2015 1:32 AM, "Roelof Wobben" <<a href="mailto:r.wobben@home.nl" target="_blank">r.wobben@home.nl</a>> wrote:<br>
                ><br>
                > Hello, <br>
                ><br>
                > To practice recursion I try to make some functions
                of Data list myself on the recursive way.<br>
                ><br>
                > First I will try last.<br>
                ><br>
                > So I did this : <br>
                ><br>
                > -- | Main entry point to the application.<br>
                > module Main where<br>
                ><br>
                > -- | The main entry point.<br>
                > last' :: [a] -> a <br>
                > last' [] = [] <br>
                > last' (x:xs) = last xs<br>
                ><br>
                ><br>
                > but now I see this error message : <br>
                ><br>
                > src/Main.hs@6:12-6:14<br>
                > Couldn't match expected type<br>
                > a<br>
                > with actual type<br>
                > [t0]<br>
                > a<br>
                > is a rigid type variable bound by the type
                signature for last' :: [a] -> a at
                /home/app/isolation-runner-work/projects/112712/session.207/src/src/Main.hs:5:10

                Relevant bindings include last' :: [a] -> a (bound at
                /home/app/isolation-runner-work/projects/112712/session.207/src/src/Main.hs:6:1)

                …<br>
                ><br>
                > I my oponion I have said that the input is a array
                and the output a string, </p>
              <p dir="ltr">Except for saying list instead of array, I'd
                agree with that. But when you write last' [] = [], the
                output is [], which does not have the expected type of
                strong. So the actual type is a list.</p>
              <p dir="ltr">You need to return a string.</p>
              <br>
              <fieldset></fieldset>
              <br>
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            <br>
          </div>
          <div bgcolor="#FFFFFF" text="#000000"> Thanks, <br>
            <br>
            I did change it to this : <br>
          </div>
          <div bgcolor="#FFFFFF" text="#000000"> <br>
            -- | Main entry point to the application.<br>
            module Main where<br>
            <br>
            -- | The main entry point.<br>
            last' :: [a] -> a <br>
          </div>
          <div bgcolor="#FFFFFF" text="#000000"> last' [x] = x <br>
          </div>
          <div bgcolor="#FFFFFF" text="#000000"> last' (x:xs) = last xs<br>
            <br>
          </div>
          <div bgcolor="#FFFFFF" text="#000000"> So I have to look at
            another way to say if there is a empty list then there is no
            answer. <br>
            And when I run it  i see this error message : <br>
            <br>
            GHC threw an exception : Not in scope: ‘Main.main’</div>
          <div bgcolor="#FFFFFF" text="#000000"><br>
            <br>
            Roelof<br>
            <br>
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