diff options
| author | Braxton Hall | 2022-10-26 08:28:10 +0000 |
|---|---|---|
| committer | GitHub | 2022-10-26 08:28:10 +0000 |
| commit | 1e86129a200b7bc2b0120c9eb102952ee78b5c49 (patch) | |
| tree | c317cee42a9b35bfcb93e57b54b078738f5a352f /entries/funemy | |
| parent | 47f320cecf3d5caf67bda5845d2230cdb9b32708 (diff) | |
| parent | 97e2651a917e68b5e59595fe538b97d65f4508e7 (diff) | |
Merge pull request #47 from funemy/main
your favorite $ sign
Diffstat (limited to 'entries/funemy')
| -rw-r--r-- | entries/funemy/.gitignore | 2 | ||||
| -rw-r--r-- | entries/funemy/haskell/morphib.hs | 43 |
2 files changed, 45 insertions, 0 deletions
diff --git a/entries/funemy/.gitignore b/entries/funemy/.gitignore index 3d2fbd5..9211bbd 100644 --- a/entries/funemy/.gitignore +++ b/entries/funemy/.gitignore @@ -2,3 +2,5 @@ *.agdai *.smt2 **/.koka/* +*.hi +*.o diff --git a/entries/funemy/haskell/morphib.hs b/entries/funemy/haskell/morphib.hs new file mode 100644 index 0000000..1fae449 --- /dev/null +++ b/entries/funemy/haskell/morphib.hs @@ -0,0 +1,43 @@ +-- Fantastic Morphisms +newtype Free f = Free {unFree :: f (Free f)} + +cata :: Functor f => (f a -> a) -> Free f -> a +cata phi (Free x) = phi $ fmap (cata phi) x + +ana :: Functor f => (a -> f a) -> a -> Free f +ana phi x = Free $ fmap (ana phi) (phi x) + +data FibF a = + Fib0 + | Fib1 + | FibN a a + deriving (Eq, Show) + +instance Functor FibF where + fmap f Fib0 = Fib0 + fmap f Fib1 = Fib1 + fmap f (FibN l r) = FibN (f l) (f r) + +type Fib a = Free FibF + +gen :: Int -> FibF Int +gen 0 = Fib0 +gen 1 = Fib1 +gen n = FibN (n-1) (n-2) + +interp :: FibF Int -> Int +interp Fib0 = 0 +interp Fib1 = 1 +interp (FibN l r) = l + r + +bif :: Int -> Fib Int +bif = ana gen + +fib' :: Fib Int -> Int +fib' = cata interp + +fib :: Int -> Int +fib = fib' . bif + +main :: IO () +main = print (fib 14) |