haskell-lectures/VL1/content/VL1_lists4.tex

19 lines
833 B
TeX
Raw Normal View History

Haskell also supports \textbf{list comprehension} which is basically syntactic sugar for what we already know from maths.\\
Let's define a set that contains the first ten even natural numbers:\\
\pause
$S = \{2 \times x\ |\ x \in \mathbb{N},\ x \leq 10\}$
\vspace{\baselineskip}
\pause
\\
How does this look in haskell?
\pause
\begin{haskellcode*}{bgcolor=mygrey,frame=single,numbers=none,label=GHCi}
> [ 2 * x | x <- [1..10]]
\end{haskellcode*}
\pause
Now let's say we want all numbers between 50 and 100 that have the remainder 0 when divided by 12:
\pause
\begin{haskellcode*}{bgcolor=mygrey,frame=single,numbers=none,label=GHCi}
> [x | x <- [50..100], mod x 12 == 0]
\end{haskellcode*}
\hinline{x <- [50..100]} is the binding, while \hinline{mod x 12 == 0} is the predicate, separated by a comma. We can have multiple predicates.