haskell-lectures/VL2/content/VL2_currying5.tex
2015-04-21 00:24:24 +02:00

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So in mathematical terms you can say:\\
$f : A_1 \times ... \times A_n \mapsto B$
\vspace{\baselineskip}
\\
gets modified into:\\
\pause
$f' : A_1 \mapsto (A_2 \mapsto (\ ...\ (A_n \mapsto B)))$
\vspace{\baselineskip}
\\
\pause
Did you just notice the braces? They are \textbf{very} important! So, currying is \emph{right}-associative which means that these two signatures are equivalent:
\begin{haskellcode}
f :: Int -> Int -> Int
f :: Int -> (Int -> Int)
-- but this is NOT the same
f :: (Int -> Int) -> Int
\end{haskellcode}
On the other hand function application is \emph{left}-associative, so \hinline{f 3 2} is just a shorthand of \hinline{(f 3) 2}. Makes sense?