Now you know how a regular function looks like, e.g:
\begin{haskellcode}
f :: Int -> Int
f x = x + 1
\end{haskellcode}
But now imagine we need a helper function which is very specific to the current function. In C we would have to define this new helper function at top-level and would probably make it \cinline{static}.
\pause
\vspace{\baselineskip}
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Haskell allows us to \textbf{inline} functions in a few more ways, e.g.:
\begin{itemizep}
\item with \hinline{where}
\item with \hinline{let...in}
\item anonymously (lambda abstraction)
\end{itemizep}
\slidep
A lot of Haskellers really dislike if you put non-generic functions at the top level. So you can still have atomic pieces, but inline the parts which are very specific to the current function.