16 lines
692 B
TeX
16 lines
692 B
TeX
All those 3 functions look almost the same. Since haskell is about abstraction, we would never really write any of those like that. Instead, we will write a function that generalizes all 3.
|
|
\vspace{\baselineskip}
|
|
\\
|
|
\pause
|
|
I'll give you the type signature, can you guess how the implementation looks like?
|
|
\begin{haskellcode}
|
|
map :: (a -> b) -> [a] -> [b]
|
|
\end{haskellcode}
|
|
Solution?
|
|
\pause
|
|
\begin{haskellcode}
|
|
map :: (a -> b) -> [a] -> [b]
|
|
map f [] = []
|
|
map f (x:xs) = f x : map f xs
|
|
\end{haskellcode}
|
|
So we don't really know what the function \hinline{f} does, but we know that it converts one element of the list to something else. We \emph{map} a function over a list! Hence the name. |