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Hello, <br>
<br>
I try to re implement ++ <br>
<br>
So far I have this ; <br>
<br>
plusplus' :: [a] -> [a] -> [a]<br>
plusplus' [] (xs) = xs <br>
plusplus' [] [] = [] <br>
plusplus' (xs) [] = xs<br>
plusplus' (x:xs) yx = plusplus' xs x:yx<br>
<br>
main = print . plusplus' $ [1,2] [3,4]<br>
<br>
<br>
But I still get this error message : <br>
<br>
<div class="ide-error-span">src/Main.hs@5:23-5:37 </div>
<div class="ide-error-msg"><span>Couldn't match expected type </span>
<div class="CodeMirror cm-s-default" style="font-size: 14px;"><span
class="cm-variable">a</span></div>
<span> with actual type </span>
<div class="CodeMirror cm-s-default" style="font-size: 14px;">[<span
class="cm-variable">a</span>]</div>
<span> </span>
<div class="CodeMirror cm-s-default" style="font-size: 14px;"><span
class="cm-variable">a</span></div>
<span> is a rigid type variable bound by the type signature for
plusplus' :: [a] -> [a] -> [a] at
/home/app/isolation-runner-work/projects/112825/session.207/src/src/Main.hs:1:14
Relevant
bindings include yx :: [a] (bound at
/home/app/isolation-runner-work/projects/112825/session.207/src/src/Main.hs:5:18)
xs :: [a] (bound at
/home/app/isolation-runner-work/projects/112825/session.207/src/src/Main.hs:5:14)
x :: a (bound at
/home/app/isolation-runner-work/projects/112825/session.207/src/src/Main.hs:5:12)
plusplus' :: [a] -> [a] -> [a] (bound at
/home/app/isolation-runner-work/projects/112825/session.207/src/src/Main.hs:2:1)</span><span
title="Click to show/hide extra information"
class="ide-error-collapse-btn"> …<br>
<br>
<br>
</span></div>
<br>
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