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<div class="moz-cite-prefix">Roelof Wobben schreef op 1-2-2015 om
12:08:<br>
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<blockquote cite="mid:54CE091B.2070301@home.nl" type="cite">
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<div class="moz-cite-prefix">Bob Ippolito schreef op 1-2-2015 om
11:24:<br>
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<blockquote
cite="mid:CACwMPm86AgNr6DQZMmJFoSqZiT-G+7B1w3Ck5dDqjJncoopRew@mail.gmail.com"
type="cite">
<div dir="ltr">The goal is to solve the problem as stated such
that it would work for *any* example, not just that one. It's
very easy to come up with an example that does not work with
your implementation.
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<div>Perhaps you should read the source for the lists module,
and take the time to try and understand it. <a
moz-do-not-send="true"
href="https://github.com/erlang/otp/blob/maint/lib/stdlib/src/lists.erl">https://github.com/erlang/otp/blob/maint/lib/stdlib/src/lists.erl</a></div>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Sun, Feb 1, 2015 at 2:14 AM,
Roelof Wobben <span dir="ltr"><<a moz-do-not-send="true"
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">Hello,<br>
<br>
I have this exercise of the Erlang programming book.<br>
<br>
Write a function that, given a list of lists, will
concatenate them.<br>
Example:<br>
concatenate([[1,2,3], [], [4, five]]) ⇒ [1,2,3,4,five].<br>
Hint: you will have to use a helpfunction and concatenate
the lists in several steps.<br>
<br>
But I do not need to use a helper function because it can
be solved like this :<br>
<br>
concatenate( [List1 , List2 , List3] ) -><br>
List1 ++ List2 ++ List3.<br>
<br>
Or is this not the solution that is meant on this exercise
?<br>
Do I need to solve it by using pattern matching ?<br>
<br>
Roelof<br>
<br>
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<br>
Thanks, I will do this,<br>
<br>
But there is one problem.<br>
<br>
The source is full of -spec and in programming erlang that is
explained in chapter 18 where Im trying exercises of chapter 3.<br>
<br>
Roelof<br>
<br>
<br>
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<br>
<br>
This solution better ?<br>
<br>
concatenate([]) -><br>
[].<br>
<br>
concatenate([List] ) -><br>
concatenate2(List1, []).<br>
<br>
concatenate2([], List) -><br>
List; <br>
<br>
concatenate2([Head| Tail], List) -><br>
concatenate2(Tail, [Head | List])<br>
<br>
Roelof<br>
<br>
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