constraints-extras (empty) → 0.1.0.0

raw patch · 6 files changed

+134/−0 lines, 6 filesdep +basedep +constraintsdep +template-haskellsetup-changed

Dependencies added: base, constraints, template-haskell

Files

ChangeLog.md +5/−0
LICENSE +30/−0
Setup.hs +2/−0
constraints-extras.cabal +18/−0
src/Data/Constraint/Extras.hs +26/−0
src/Data/Constraint/Extras/TH.hs +53/−0

+ ChangeLog.md view

@@ -0,0 +1,5 @@+# Revision history for argdict++## 0.1.0.0  -- YYYY-mm-dd++* First version. Released on an unsuspecting world.

+ LICENSE view

@@ -0,0 +1,30 @@+Copyright (c) 2018, Cale Gibbard, Ali Abrar++All rights reserved.++Redistribution and use in source and binary forms, with or without+modification, are permitted provided that the following conditions are met:++    * Redistributions of source code must retain the above copyright+      notice, this list of conditions and the following disclaimer.++    * Redistributions in binary form must reproduce the above+      copyright notice, this list of conditions and the following+      disclaimer in the documentation and/or other materials provided+      with the distribution.++    * Neither the name of Cale Gibbard, Ali Abrar nor the names of other+      contributors may be used to endorse or promote products derived+      from this software without specific prior written permission.++THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+ Setup.hs view

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

+ constraints-extras.cabal view

@@ -0,0 +1,18 @@+name:                constraints-extras+version:             0.1.0.0+synopsis:            Utility package for constraints+license:             BSD3+license-file:        LICENSE+author:              Cale Gibbard, Ali Abrar+maintainer:          maintainer@obsidian.systems+copyright:           Obsidian Systems LLC+build-type:          Simple+extra-source-files:  ChangeLog.md+cabal-version:       >=1.10++library+  exposed-modules:     Data.Constraint.Extras, Data.Constraint.Extras.TH+  other-extensions:    CPP, ExistentialQuantification, FlexibleInstances, GADTs, LambdaCase, MultiParamTypeClasses, QuasiQuotes, StandaloneDeriving, TypeFamilies, TypeOperators, ConstraintKinds, TemplateHaskell+  build-depends:       base >=4.9 && <4.11, constraints >= 0.9 && < 0.10, template-haskell >=2.11 && <2.12+  hs-source-dirs:      src+  default-language:    Haskell2010

+ src/Data/Constraint/Extras.hs view

@@ -0,0 +1,26 @@+{-# LANGUAGE CPP #-}+{-# LANGUAGE ExistentialQuantification #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE GADTs #-}+{-# LANGUAGE LambdaCase #-}+{-# LANGUAGE MultiParamTypeClasses #-}+{-# LANGUAGE QuasiQuotes #-}+{-# LANGUAGE StandaloneDeriving #-}+{-# LANGUAGE TypeFamilies #-}+{-# LANGUAGE TypeOperators #-}+{-# LANGUAGE ConstraintKinds #-}++module Data.Constraint.Extras where++import Data.Constraint++-- | Provides proof of the existence of a constraint on a GADT+class ArgDict f where+  type ConstraintsFor (c :: * -> Constraint) f :: Constraint+  argDict :: ConstraintsFor c f => f a -> Dict (c a)++type Has c f = (ArgDict f, ConstraintsFor c f)++-- | Allows explicit specification of constraint implication+class Implies1 c d where+  implies1 :: c a :- d a

+ src/Data/Constraint/Extras/TH.hs view

@@ -0,0 +1,53 @@+{-# LANGUAGE CPP #-}+{-# LANGUAGE LambdaCase #-}+{-# LANGUAGE QuasiQuotes #-}+{-# LANGUAGE TemplateHaskell #-}+module Data.Constraint.Extras.TH where++import Data.Constraint.Extras+import Control.Monad+import Data.Constraint+import Data.Semigroup+import Language.Haskell.TH++deriveArgDict :: Name -> Q [Dec]+deriveArgDict n = do+  ts <- gadtResults n+  c <- newName "c"+  let xs = map (AppT (VarT c)) ts+      l = length xs+      constraints = foldl AppT (TupleT l) xs+  [d| instance ArgDict $(pure $ ConT n) where+        type ConstraintsFor $(varT c) $(pure $ ConT n) = $(pure constraints)+        argDict = $(LamCaseE <$> matches)+    |]+  where+    matches :: Q [Match]+    matches = do+      x <- newName "x"+      reify n >>= \case+        TyConI (DataD _ _ _ _ cons _) -> pure $ concat $ flip map cons $ \case+          GadtC [name] _ (AppT (ConT _) (VarT _)) ->+            [Match (ConP name [VarP x]) (NormalB $ AppE (VarE 'argDict) (VarE x)) []]+          GadtC [name] _ _ ->+            [Match (RecP name []) (NormalB $ ConE 'Dict) []]+          ForallC _ _ (GadtC [name] _ (AppT (ConT _) (VarT _))) ->+            [Match (ConP name [VarP x]) (NormalB $ AppE (VarE 'argDict) (VarE x)) []]+          ForallC _ _ (GadtC [name] _ _) ->+            [Match (RecP name []) (NormalB $ ConE 'Dict) []]+          NormalC name [(_, AppT (ConT _) (VarT _))] ->+            [Match (ConP name [VarP x]) (NormalB $ AppE (VarE 'argDict) (VarE x)) []]+          a -> error $ "deriveArgDict matches: Unmatched 'Dec': " <> show a+        a -> error $ "deriveArgDict matches: Unmatched 'Info': " <> show a++gadtResults :: Name -> Q [Type]+gadtResults n = reify n >>= \case+  TyConI (DataD _ _ _ _ cons _) -> fmap concat $ forM cons $ \case+    GadtC _ _ (AppT (ConT _) (VarT _)) -> return []+    GadtC _ _ (AppT _ (AppT (ConT _) (VarT _))) -> return []+    GadtC _ _ (AppT _ typ) -> return [typ]+    ForallC _ _ (GadtC _ _ (AppT (ConT _) (VarT _))) -> return []+    ForallC _ _ (GadtC _ _ (AppT _ (AppT (ConT _) (VarT _)))) -> return []+    ForallC _ _ (GadtC _ _ (AppT _ typ)) -> return [typ]+    _ -> return []+  a -> error $ "gadtResults: Unmatched 'Info': " <> show a