haskell-lectures/VL1/content/VL1_what_is_haskell2.tex

Think of haskell functions as regular \emph{mathematical} functions.
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\begin{center}
\includegraphics*[scale=0.6]{./images/function-machine.png}
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\begin{itemizep}
\item does this function write to the hard drive?
\item does the output depend on anything else except the input (e.g. time, environment, ...)?
\end{itemizep}
\slidep
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It's all about \emph{input} and \emph{output} of functions! And that's it. Nothing else to worry about.