Hello
Just testing some stuff. Here’s some code for Haskell’s Functor
typeclass:
class Functor f where
fmap :: (a -> b) -> f a -> f b
(<$) :: a -> f b -> f a
(<$) = fmap . const
And here is some math:
$$
\begin{align} \cdots\rightarrow H_{n+1}(X)\,&\xrightarrow{\partial_*}\,H_{n}(A\cap B)\,\rightarrow\,H_{n}(A)\oplus H_{n}(B)\,\rightarrow\,H_{n}(X)\xrightarrow{\partial_*}\\ &\quad\xrightarrow{\partial_*}\,H_{n-1} (A\cap B)\rightarrow \cdots\rightarrow H_0(A)\oplus H_0(B)\,\rightarrow\,H_0(X)\rightarrow\,0. \end{align}
$$