diff --git a/site-src/burrito.mdx b/site-src/burrito.mdx deleted file mode 100644 index 615f018..0000000 --- a/site-src/burrito.mdx +++ /dev/null @@ -1,58 +0,0 @@ ---- -title: "Monads: Why and how" -description: I could not repress the urge to make a monad explainer any longer. Did you know that a monad is a monoid in the category of endofunctors? -tags: post,short,haskell -date: 2026-05-06 01:20:10 -5 ---- - -I acknowledge that [the world wide web has one hundred trillion monad explainers.](https://wiki.haskell.org/Monad_tutorials_timeline) - -![Chart titled "Number of known monad tutorials. It grew from zero in 1991 to fifteenish in 2005 before increasing in speed and ending at about 120 in 2023](https://wiki.haskell.org/wikiupload/2/23/Monad-tutorials-chart.png) - -## Why monads -In the land of Haskell and friends, we love referential transparency. -We greatly appreciate that -```haskell -let x = 1 in x + x -``` -will always have the same result as -```haskell -1 + 1 -``` - -In languages where (almost) no functions have unmarked side-effects, like Haskell, you can even be confident that -```haskell -let x = f y in x + x -``` -is the same as -```haskell -(f y) + (f y) -``` - -This is a truly excellent property to have, but it causes some problems when your program starts interacting with the world. - -Aside from referential transparency, we don't want to fix evaluation order if we don't have to; -giving the compiler more freedom to reorder evaluation lets it perform more optimizations. -And we always want more optimizations. - -But, quite often, we *need* things to happen in a specific order. - -Monads let us do two things: -1. Order operations -2. Use past results to decide what to do next - -## How monads -Easy: -```haskell -class Monad m where - (>>=) :: m a -> (a -> m b) -> m b - pure :: a -> m a -``` - -`>>=`, pronounced `bind`, gives us ordering and lets us use past results to decide what to do next. - -The fact that it gives us ordering is made more clear if we define `>>`, which ignores its result: -```haskell -(>>) :: m a -> m b -> m b -a >> b = a >>= \_ -> b -``` diff --git a/site-src/spout/index.html b/site-src/spout/index.html index a99a773..495cf1e 100644 --- a/site-src/spout/index.html +++ b/site-src/spout/index.html @@ -1,9 +1,9 @@ spout - + - + + + + + + +