diff options
Diffstat (limited to 'html-test/src')
-rw-r--r-- | html-test/src/BundledPatterns.hs | 110 | ||||
-rw-r--r-- | html-test/src/BundledPatterns2.hs | 10 |
2 files changed, 120 insertions, 0 deletions
diff --git a/html-test/src/BundledPatterns.hs b/html-test/src/BundledPatterns.hs new file mode 100644 index 00000000..443e64fa --- /dev/null +++ b/html-test/src/BundledPatterns.hs @@ -0,0 +1,110 @@ +{-# LANGUAGE DataKinds, GADTs, KindSignatures, PatternSynonyms, TypeOperators, + ViewPatterns #-} +module BundledPatterns (Vec(Nil,(:>)), RTree (LR,BR)) where + +import GHC.TypeLits +import Prelude hiding (head, tail) +import Unsafe.Coerce + +-- | Fixed size vectors. +-- +-- * Lists with their length encoded in their type +-- * 'Vec'tor elements have an __ASCENDING__ subscript starting from 0 and +-- ending at @'length' - 1@. +data Vec :: Nat -> * -> * where + Nil :: Vec 0 a + Cons :: a -> Vec n a -> Vec (n + 1) a + +infixr 5 `Cons` + +-- | Add an element to the head of a vector. +-- +-- >>> 3:>4:>5:>Nil +-- <3,4,5> +-- >>> let x = 3:>4:>5:>Nil +-- >>> :t x +-- x :: Num a => Vec 3 a +-- +-- Can be used as a pattern: +-- +-- >>> let f (x :> y :> _) = x + y +-- >>> :t f +-- f :: Num a => Vec ((n + 1) + 1) a -> a +-- >>> f (3:>4:>5:>6:>7:>Nil) +-- 7 +-- +-- Also in conjunctions with (':<'): +-- +-- >>> let g (a :> b :> (_ :< y :< x)) = a + b + x + y +-- >>> :t g +-- g :: Num a => Vec ((((n + 1) + 1) + 1) + 1) a -> a +-- >>> g (1:>2:>3:>4:>5:>Nil) +-- 12 +pattern (:>) :: a -> Vec n a -> Vec (n + 1) a +pattern (:>) x xs <- ((\ys -> (head ys,tail ys)) -> (x,xs)) + where + (:>) x xs = Cons x xs + +infixr 5 :> + +head :: Vec (n + 1) a -> a +head (x `Cons` _) = x + +tail :: Vec (n + 1) a -> Vec n a +tail (_ `Cons` xs) = unsafeCoerce xs + +-- | Perfect depth binary tree. +-- +-- * Only has elements at the leaf of the tree +-- * A tree of depth /d/ has /2^d/ elements. +data RTree :: Nat -> * -> * where + LR_ :: a -> RTree 0 a + BR_ :: RTree d a -> RTree d a -> RTree (d+1) a + +textract :: RTree 0 a -> a +textract (LR_ x) = x +{-# NOINLINE textract #-} + +tsplit :: RTree (d+1) a -> (RTree d a,RTree d a) +tsplit (BR_ l r) = (unsafeCoerce l, unsafeCoerce r) +{-# NOINLINE tsplit #-} + +-- | Leaf of a perfect depth tree +-- +-- >>> LR 1 +-- 1 +-- >>> let x = LR 1 +-- >>> :t x +-- x :: Num a => RTree 0 a +-- +-- Can be used as a pattern: +-- +-- >>> let f (LR a) (LR b) = a + b +-- >>> :t f +-- f :: Num a => RTree 0 a -> RTree 0 a -> a +-- >>> f (LR 1) (LR 2) +-- 3 +pattern LR :: a -> RTree 0 a +pattern LR x <- (textract -> x) + where + LR x = LR_ x + +-- | Branch of a perfect depth tree +-- +-- >>> BR (LR 1) (LR 2) +-- <1,2> +-- >>> let x = BR (LR 1) (LR 2) +-- >>> :t x +-- x :: Num a => RTree 1 a +-- +-- Case be used a pattern: +-- +-- >>> let f (BR (LR a) (LR b)) = LR (a + b) +-- >>> :t f +-- f :: Num a => RTree 1 a -> RTree 0 a +-- >>> f (BR (LR 1) (LR 2)) +-- 3 +pattern BR :: RTree d a -> RTree d a -> RTree (d+1) a +pattern BR l r <- ((\t -> (tsplit t)) -> (l,r)) + where + BR l r = BR_ l r diff --git a/html-test/src/BundledPatterns2.hs b/html-test/src/BundledPatterns2.hs new file mode 100644 index 00000000..5e9a83a7 --- /dev/null +++ b/html-test/src/BundledPatterns2.hs @@ -0,0 +1,10 @@ +{-# LANGUAGE DataKinds, GADTs, KindSignatures, PatternSynonyms, TypeOperators, + ViewPatterns #-} +module BundledPatterns2 (Vec((:>), Empty), RTree(..)) where + +import GHC.TypeLits + +import BundledPatterns + +pattern Empty :: Vec 0 a +pattern Empty <- Nil |