diff --git a/Changelog b/Changelog new file mode 100644 --- /dev/null +++ b/Changelog @@ -0,0 +1,24 @@ +0.3.2 (2015-10-29) + * add Eq instances for `IVar` and `MIChan` + +0.3.1 (2015-07-02) + * fix building with ghc 7.8 + +0.3 (2012-07-24) + * change NonTermination to a custom BlockedIndefinitelyOnIVar + exception, and require base >= 4. (using NonTermination leads to + <> messages) + +0.2 (2012-07-23) + * change BlockedIndefinitely exception (gone since ghc 7.0) to + NonTermination + +0.1.0.2 (2009-06-03) + * depend on base < 5 instead of base. + +0.1.0.1 (2009-01-11) + * make Data.IVar.Simple.tryWrite exception safe + (noticed by Chris Kuklewicz) + +0.1.0.0 (2009-01-11) + * initial version diff --git a/HISTORY b/HISTORY deleted file mode 100644 --- a/HISTORY +++ /dev/null @@ -1,15 +0,0 @@ -0.3 (2012-07-24) - change NonTermination to a custom BlockedIndefinitelyOnIVar exception, - and require base >= 4. (using NonTermination leads to <> messages) - -0.2 (2012-07-23) - change BlockedIndefinitely exception (gone since ghc 7.0) to NonTermination - -0.1.0.2 (2009-06-03) - depend on base < 5 instead of base. - -0.1.0.1 (2009-01-11) - make Data.IVar.Simple.tryWrite exception safe (noticed by Chris Kuklewicz) - -0.1.0.0 (2009-01-11) - initial version diff --git a/LICENSE b/LICENSE --- a/LICENSE +++ b/LICENSE @@ -1,4 +1,4 @@ -Copyright (c) 2008-2012 Bertram Felgenhauer +Copyright (c) 2008-2015 Bertram Felgenhauer Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal diff --git a/README b/README deleted file mode 100644 --- a/README +++ /dev/null @@ -1,32 +0,0 @@ -What is this? -------------- - -ivar-simple provides immutable, write-once variables (IVars) in the -Data.IVar.Simple module. - -It also provides two more experimental channel implementations built on -top of IVars, - - Data.IVar.Simple.IChan: - multi-cast channels with write-once semantics. - - Data.IVar.Simple.MIChan: - channels with write semantics similar to Control.Concurrent.Chan - -Comparison to data-ivar ------------------------ - -Both data-ivar and ivar-simple provide a write-once variable. That's where -the similarities end: - -- Reading an IVar with data-ivar is an IO operation. In ivar-simple it's a - pure function. -- data-ivar provides a 'Reader' monoid, monad, etc. for reading from one of - several IVars. ivar-simple has no such functionality. -- The data-ivar implementation can, in principle, add arbitrary IO actions - that are called when an IVar is written. (This detail is not exposed, - however) -- Technically, ivar-simple tries for efficiency by exploiting the existing - locking structures in the RTS; in particular, reading a full IVar for a - second time is as cheap as evaluating a record selector. - I have no performance numbers for this. diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,29 @@ +## What is this? + +ivar-simple provides immutable, write-once variables (`IVar`s) in the +`Data.IVar.Simple` module. + +It also provides two more experimental channel implementations built on +top of `IVar`s, + +* `Data.IVar.Simple.IChan`: + multi-cast channels with write-once semantics. +* `Data.IVar.Simple.MIChan`: + channels with write semantics similar to Control.Concurrent.Chan + +## Comparison to data-ivar + +Both data-ivar and ivar-simple provide a write-once variable. That's where +the similarities end: + +* Reading an `IVar` with data-ivar is an `IO` operation. In ivar-simple it's + a pure function. +* data-ivar provides a `Reader` monoid, monad, etc. for reading from one of + several `IVar`s. ivar-simple has no such functionality. +* The data-ivar implementation can, in principle, add arbitrary `IO` actions + that are called when an `IVar` is written. (This detail is not exposed, + however) +* Technically, ivar-simple tries for efficiency by exploiting the existing + locking structures in the RTS; in particular, reading a full `IVar` for + a second time is as cheap as evaluating a record selector. + (I have no performance numbers for this.) diff --git a/ivar-simple.cabal b/ivar-simple.cabal --- a/ivar-simple.cabal +++ b/ivar-simple.cabal @@ -1,31 +1,36 @@ -Name: ivar-simple -Version: 0.3.1 -Category: Concurrency -Stability: experimental -Copyright: (c) 2008-2015 Bertram Felgenhauer -Maintainer: Bertram Felgenhauer -License: MIT -License-File: LICENSE -Synopsis: Write once concurrency primitives. -Description: +name: ivar-simple +version: 0.3.2 +category: Concurrency +stability: experimental +copyright: (c) 2008-2015 Bertram Felgenhauer +maintainer: Bertram Felgenhauer +license: MIT +license-file: LICENSE +synopsis: Write once concurrency primitives. +description: @IVar@s are write-once (immutable) variables. . They can be read, an operation that will block until a value was written to the variable. They can be written to exactly once. -Cabal-Version: >= 1.4 -Build-Type: Simple -Extra-Source-Files: - README - HISTORY +cabal-version: >= 1.6 +build-type: Simple +extra-source-files: + README.md + Changelog -Library - Hs-Source-Dirs: +source-repository head + type: git + location: https://github.com/int-e/ivar-simple + + +library + hs-source-dirs: src - Exposed-Modules: + exposed-modules: Data.IVar.Simple Data.IVar.Simple.IChan Data.IVar.Simple.MIChan - Build-Depends: + build-depends: base >= 4 && < 5 - Extensions: + extensions: DeriveDataTypeable diff --git a/src/Data/IVar/Simple.hs b/src/Data/IVar/Simple.hs --- a/src/Data/IVar/Simple.hs +++ b/src/Data/IVar/Simple.hs @@ -37,6 +37,11 @@ -- | A write-once (/immutable/) Variable data IVar a = IVar (MVar ()) (MVar a) a +instance Eq (IVar a) where + IVar lock1 _ _ == IVar lock2 _ _ = lock1 == lock2 + -- note: it would be possible to generalize the type to + -- eqIVar :: IVar a -> IVar b -> Bool (but would that be useful?) + -- | Create a new, empty 'IVar'. new :: IO (IVar a) new = do diff --git a/src/Data/IVar/Simple/MIChan.hs b/src/Data/IVar/Simple/MIChan.hs --- a/src/Data/IVar/Simple/MIChan.hs +++ b/src/Data/IVar/Simple/MIChan.hs @@ -29,6 +29,7 @@ -- | A multicast channel. newtype MIChan a = MIChan (MVar (IChan.IChan a)) + deriving Eq -- | Create a new multicast channel. new :: IO (MIChan a)