23 lines
1020 B
TeX
23 lines
1020 B
TeX
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Let's define something more complex. How about a tree?
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\pause
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\begin{haskellcode}
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data Tree = Leaf Char
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| Node Tree Int Tree
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\end{haskellcode}
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Uh... that looks mean. Let's examine this.\\
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\pause
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We have:
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\begin{itemizep}
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\item defined a data type \code{Tree}
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\item a constructor \code{Leaf} of type \code{Tree} with one arguments of type \code{Char}
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\item a constructor \code{Node} of type \code{Tree} with 3 arguments
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\begin{itemizep}
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\item \code{Tree}
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\item \code{Int}
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\item \code{Tree}
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\end{itemizep}
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\end{itemizep}
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\slidep
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That means: a \code{Tree} can either be a \code{Leaf} or an internal \code{Node} with two sub-trees. If we want to create a \code{Leaf}, we have to pass the constructor a \code{Char}. If we want to create a \code{Node}, we have to pass 3 arguments, in order: another \code{Tree}, an \code{Int} and yet another \code{Tree}.\\
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So we can save information in the leafs (\code{Char}) and in the internal nodes (\code{Int}).\\
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This is just an example. There are endless more ways of trees.
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