nthable (empty) → 0.1

raw patch · 3 files changed

+89/−0 lines, 3 filesdep +basedep +type-levelsetup-changed

Dependencies added: base, type-level

Files

• Data/Nthable.hs +74/−0
• Setup.lhs +4/−0
• nthable.cabal +11/−0

@@ -0,0 +1,74 @@+{-# LANGUAGE UnicodeSyntax, MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, FlexibleContexts #-}+-- | Generalizes 'Prelude.snd', 'Prelude.fst', and so on.+module Data.Nthable+where++import Data.TypeLevel.Num.Sets+import Data.TypeLevel.Num.Reps+import Data.TypeLevel.Num.Aliases++-- | A class that knows how to access the "nth" member of a+--   type.+class (Pos n) ⇒ Nthable t n a | t n → a where+	nth ∷ n → t → a+	-- ^ Example: +	--+	-- > nth d1 (1,2) == 1+	-- > nth d2 (1,2) == 2+	-- > nth d3 (1,2) == error!++instance Nthable (a,b) D1 a where nth _ (a,_) = a+instance Nthable (a,b) D2 b where nth _ (_,b) = b++instance Nthable (a,b,c) D1 a where nth _ (a,_,_) = a+instance Nthable (a,b,c) D2 b where nth _ (_,b,_) = b+instance Nthable (a,b,c) D3 c where nth _ (_,_,c) = c++instance Nthable (a,b,c,d) D1 a where nth _ (a,_,_,_) = a+instance Nthable (a,b,c,d) D2 b where nth _ (_,b,_,_) = b+instance Nthable (a,b,c,d) D3 c where nth _ (_,_,c,_) = c+instance Nthable (a,b,c,d) D4 d where nth _ (_,_,_,d) = d++instance Nthable (a,b,c,d,e) D1 a where nth _ (a,_,_,_,_) = a+instance Nthable (a,b,c,d,e) D2 b where nth _ (_,b,_,_,_) = b+instance Nthable (a,b,c,d,e) D3 c where nth _ (_,_,c,_,_) = c+instance Nthable (a,b,c,d,e) D4 d where nth _ (_,_,_,d,_) = d+instance Nthable (a,b,c,d,e) D5 e where nth _ (_,_,_,_,e) = e++instance Nthable (a,b,c,d,e,f) D1 a where nth _ (a,_,_,_,_,_) = a+instance Nthable (a,b,c,d,e,f) D2 b where nth _ (_,b,_,_,_,_) = b+instance Nthable (a,b,c,d,e,f) D3 c where nth _ (_,_,c,_,_,_) = c+instance Nthable (a,b,c,d,e,f) D4 d where nth _ (_,_,_,d,_,_) = d+instance Nthable (a,b,c,d,e,f) D5 e where nth _ (_,_,_,_,e,_) = e+instance Nthable (a,b,c,d,e,f) D6 f where nth _ (_,_,_,_,_,f) = f++instance Nthable (a,b,c,d,e,f,g) D1 a where nth _ (a,_,_,_,_,_,_) = a+instance Nthable (a,b,c,d,e,f,g) D2 b where nth _ (_,b,_,_,_,_,_) = b+instance Nthable (a,b,c,d,e,f,g) D3 c where nth _ (_,_,c,_,_,_,_) = c+instance Nthable (a,b,c,d,e,f,g) D4 d where nth _ (_,_,_,d,_,_,_) = d+instance Nthable (a,b,c,d,e,f,g) D5 e where nth _ (_,_,_,_,e,_,_) = e+instance Nthable (a,b,c,d,e,f,g) D6 f where nth _ (_,_,_,_,_,f,_) = f+instance Nthable (a,b,c,d,e,f,g) D7 g where nth _ (_,_,_,_,_,_,g) = g++-- | 'Prelude.fst' extended to work on any 'Nthable' type.+fst ∷ (Nthable n D1 a) ⇒ n → a+fst mr = nth d1 mr++-- | 'Prelude.snd' extended to work on any 'Nthable' type.+snd ∷ (Nthable n D2 a) ⇒ n → a+snd mr = nth d2 mr++thrd ∷ (Nthable n D3 a) ⇒ n → a+thrd mr = nth d3 mr++frth ∷ (Nthable n D4 a) ⇒ n → a+frth mr = nth d4 mr++ffth ∷ (Nthable n D5 a) ⇒ n → a+ffth mr = nth d5 mr++sxth ∷ (Nthable n D6 a) ⇒ n → a+sxth mr = nth d6 mr++svnth ∷ (Nthable n D7 a) ⇒ n → a+svnth mr = nth d7 mr

@@ -0,0 +1,4 @@+#! /usr/bin/env runhaskell++> import Distribution.Simple+> main = defaultMain

@@ -0,0 +1,11 @@+Name: nthable+Version: 0.1+Description: Generalization of 'fst', 'snd', etc.+License: BSD3+Category: Data Structures+Author: George Pollard+Maintainer: porges@porg.es+Build-Depends: type-level>0.2.1, base+Exposed-modules: Data.Nthable+Build-type: Simple+ghc-options: -O2 -Wall