bound-gen (empty) → 0.1.0.0

raw patch · 5 files changed

+146/−0 lines, 5 filesdep +basedep +bounddep +monad-gensetup-changed

Dependencies added: base, bound, monad-gen, mtl

Files

• LICENSE +20/−0
• README.md +9/−0
• Setup.hs +2/−0
• bound-gen.cabal +27/−0
• src/Bound/Unwrap.hs +88/−0

@@ -0,0 +1,20 @@+Copyright (c) 2014 - 2015 Danny Gratzer++Permission is hereby granted, free of charge, to any person obtaining+a copy of this software and associated documentation files (the+"Software"), to deal in the Software without restriction, including+without limitation the rights to use, copy, modify, merge, publish,+distribute, sublicense, and/or sell copies of the Software, and to+permit persons to whom the Software is furnished to do so, subject to+the following conditions:++The above copyright notice and this permission notice shall be included+in all copies or substantial portions of the Software.++THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

@@ -0,0 +1,9 @@+## bound-gen++A small library intended to make [bound][bound-hackage] easier to use+with [monad-gen][monad-gen-hackage]. This simplifies the process of+using `bound` to do nontrivial work under binders by providing a way+to unwrap a `Scope` with a globally unique free variable.++[bound-hackage]: http://hackage.haskell.org/package/bound+[monad-gen-hackage]: http://hackage.haskell.org/package/monad-gen

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

@@ -0,0 +1,27 @@+name:                bound-gen+version:             0.1.0.0+synopsis:            Unwrap Scope's with globally fresh values+description:+            It's quite common when working with bound to need to unwrap a @Scope@.+            In order to ensure that this can be done safely, without shadowing+            any existing free variables, @bound-gen@ glues @monad-gen@'s fresh+            value monad into @bound@.+license:             MIT+license-file:        LICENSE+author:              Danny Gratzer+maintainer:          jozefg@cmu.edu+category:            Compilers/Interpreters+build-type:          Simple+extra-source-files:  README.md+cabal-version:       >=1.10+source-repository head+  type: git+  location: http://github.com/jozefg/bound-gen+library+  exposed-modules:     Bound.Unwrap+  build-depends:       base >=4.0 && < 5+                     , bound+                     , monad-gen >= 0.3+                     , mtl >= 2+  hs-source-dirs:      src+  default-language:    Haskell2010

@@ -0,0 +1,88 @@+{-# LANGUAGE FlexibleContexts #-}+{-# LANGUAGE ConstraintKinds #-}+module Bound.Unwrap ( Fresh+                    , name+                    , freshify+                    , Counter+                    , UnwrapT+                    , Unwrap+                    , runUnwrapT+                    , runUnwrap+                    , unwrap+                    , unwrapAll) where+import Bound+import Control.Monad.Identity+import Control.Applicative+import Control.Monad.Gen++data Fresh a = Fresh { fresh :: !Int+                     , uname :: a }+             deriving (Eq, Ord)++instance Show a => Show (Fresh a) where+  show (Fresh i a) = show i ++ '.' : show a++-- | Create a name. This name isn't unique at all at this point. Once+-- you have a name you can pass it to freshify to render it unique+-- within the current monadic context.+name :: a -> Fresh a+name = Fresh 0++-- | @erase@ drops the information in a 'Fresh' that makes it globally+-- unique and gives you back the user supplied name. For obvious+-- reasons, @erase@ isn't injective. It is the case that+--+-- @+--    erase . name  = id+--    name . erase /= id+-- @+erase :: Fresh a -> a+erase = uname++-- Keeping this opaque, but I don't want *another*+-- monad for counting dammit. I built one and that was enough.+newtype Counter = Counter {getCounter :: Int}++-- | A specialized version of 'GenT' used for unwrapping things.+type UnwrapT = GenT Counter+type Unwrap = Gen Counter++-- | A specialized constraint for monads who know how to unwrap+-- things.+type MonadUnwrap m = MonadGen Counter m++runUnwrapT :: Monad m => UnwrapT m a -> m a+runUnwrapT = runGenTWith (successor $ Counter . succ . getCounter)+                         (Counter 0)++runUnwrap :: Unwrap a -> a+runUnwrap = runIdentity . runUnwrapT++-- | Render a name unique within the scope of a monadic computation.+freshify :: MonadUnwrap => Fresh a -> m (Fresh a)+freshify nm = (\i -> nm{fresh = i}) <$> fmap getCounter gen++-- | Create a name which is unique within the scope of a monadic+-- computation.+nameF :: MonadUnwrap m => a -> m (Fresh a)+nameF = freshify . name++-- | Given a scope which binds one variable, unwrap it with a+-- variable. Note that @unwrap@ will take care of @freshify@ing the+-- varable.+unwrap :: (Monad f, Functor m, MonadUnwrap m)+          => Fresh a+          -> Scope () f (Fresh a)+          -> m (Fresh a, f (Fresh a))+unwrap nm s = fmap head <$> unwrapAll nm [s]++-- | Given a list of scopes which bind one variable, unwrap them all+-- with the same variable. Note that @unwrapAll@ will take care of+-- @freshify@ing the variable.+unwrapAll :: (Monad f, MonadUnwrap m)+             => Fresh a+             -> [Scope () f (Fresh a)]+             -> m (Fresh a, [f (Fresh a)])+unwrapAll nm ss = do+  fnm <- freshify nm+  return $ (fnm, map (instantiate1 $ return fnm) ss)