Merge pull request #119 from natefaubion/avar-updates

AVar updates

Author: natefaubion

README.md

@@ -212,7 +212,7 @@ The `Control.Monad.Aff.AVar` module contains asynchronous variables, which
 are very similar to Haskell's `MVar`.
 
 `AVar`s represent a value that is either full or empty. Calling `takeVar` on
-an empty `AVar` will queue until it is filled by a matching `putVar`.
+an empty `AVar` will queue until it is filled by a `putVar`.
 
 ```purescript
 example = do
@@ -230,22 +230,23 @@ example = do
 > Got a value: hello
 ```
 
-Likewise, calling `putVar` will queue until it is taken:
+Likewise, calling `putVar` on a filled `AVar` will queue until it is emptied by
+a `takeVar`.
 
 ```purescript
 example = do
-  var <- makeEmptyVar
+  var <- makeVar "hello"
   _ <- forkAff do
     delay (Milliseconds 100.0)
     value <- takeVar var
     log $ "Got a value: " <> value
-  putVar var "hello"
-  log "Value taken"
+  putVar var "next"
+  log "Value put"
 ```
 ```
 (Waits 100ms)
-> Value taken
 > Got a value: hello
+> Value put
 ```
 
 These combinators (and a few more) can be used as the building blocks for

bower.json

@@ -27,7 +27,7 @@
     "purescript-free": "^4.0.1",
     "purescript-st": "^3.0.0",
     "purescript-type-equality": "^2.1.0",
-    "purescript-avar": "^1.0.1"
+    "purescript-avar": "^2.0.0"
   },
   "devDependencies": {
     "purescript-partial": "^1.2.0",

src/Control/Monad/Aff/AVar.purs

@@ -2,7 +2,10 @@ module Control.Monad.Aff.AVar
   ( module Control.Monad.Eff.AVar
   , makeVar
   , makeEmptyVar
+  , status
   , isEmptyVar
+  , isFilledVar
+  , isKilledVar
   , takeVar
   , tryTakeVar
   , putVar
@@ -15,7 +18,7 @@ module Control.Monad.Aff.AVar
 import Prelude
 import Control.Monad.Aff (Aff, Canceler(..), makeAff)
 import Control.Monad.Eff (Eff)
-import Control.Monad.Eff.AVar (AVar, AVAR)
+import Control.Monad.Eff.AVar (AVar, AVAR, AVarStatus(..), isEmpty, isFilled, isKilled)
 import Control.Monad.Eff.AVar as AVar
 import Control.Monad.Eff.Class (liftEff)
 import Control.Monad.Eff.Exception (Error)
@@ -32,10 +35,22 @@ makeVar = liftEff <<< AVar.makeVar
 makeEmptyVar ∷ ∀ eff a. Aff (avar ∷ AVAR | eff) (AVar a)
 makeEmptyVar = liftEff AVar.makeEmptyVar
 
--- | Synchronously checks whether an AVar currently has a value.
+-- | Synchronously checks the status of an AVar.
+status ∷ ∀ eff a. AVar a → Aff (avar ∷ AVAR | eff) (AVar.AVarStatus a)
+status = liftEff <<< AVar.status
+
+-- | Synchronously checks whether an AVar currently is empty.
 isEmptyVar ∷ ∀ eff a. AVar a → Aff (avar ∷ AVAR | eff) Boolean
 isEmptyVar = liftEff <<< AVar.isEmptyVar
 
+-- | Synchronously checks whether an AVar currently has a value.
+isFilledVar ∷ ∀ eff a. AVar a → Aff (avar ∷ AVAR | eff) Boolean
+isFilledVar = liftEff <<< AVar.isFilledVar
+
+-- | Synchronously checks whether an AVar has been killed.
+isKilledVar ∷ ∀ eff a. AVar a → Aff (avar ∷ AVAR | eff) Boolean
+isKilledVar = liftEff <<< AVar.isKilledVar
+
 -- | Takes the AVar value, leaving it empty. If the AVar is already empty,
 -- | the callback will be queued until the AVar is filled. Multiple takes will
 -- | resolve in order as the AVar fills.
@@ -52,15 +67,15 @@ tryTakeVar = liftEff <<< AVar.tryTakeVar
 -- | Sets the value of the AVar. If the AVar is already filled, it will be
 -- | queued until the value is emptied. Multiple puts will resolve in order as
 -- | the AVar becomes available.
-putVar ∷ ∀ eff a. AVar a → a → Aff (avar ∷ AVAR | eff) Unit
-putVar avar value = makeAff \k → do
-  c ← AVar.putVar avar value k
+putVar ∷ ∀ eff a. a → AVar a → Aff (avar ∷ AVAR | eff) Unit
+putVar value avar = makeAff \k → do
+  c ← AVar.putVar value avar k
   pure (toCanceler c)
 
 -- | Attempts to synchronously fill an AVar. If the AVar is already filled,
 -- | this will do nothing. Returns true or false depending on if it succeeded.
-tryPutVar ∷ ∀ eff a. AVar a → a → Aff (avar ∷ AVAR | eff) Boolean
-tryPutVar avar = liftEff <<< AVar.tryPutVar avar
+tryPutVar ∷ ∀ eff a. a → AVar a → Aff (avar ∷ AVAR | eff) Boolean
+tryPutVar value = liftEff <<< AVar.tryPutVar value
 
 -- | Reads the AVar value. Unlike `takeVar`, this will not leave the AVar empty.
 -- | If the AVar is empty, this will queue until it is filled. Multiple reads
@@ -77,5 +92,5 @@ tryReadVar = liftEff <<< AVar.tryReadVar
 
 -- | Kills the AVar with an exception. All pending and future actions will
 -- | resolve immediately with the provided exception.
-killVar ∷ ∀ eff a. AVar a → Error → Aff (avar ∷ AVAR | eff) Unit
-killVar avar = liftEff <<< AVar.killVar avar
+killVar ∷ ∀ eff a. Error → AVar a → Aff (avar ∷ AVAR | eff) Unit
+killVar error = liftEff <<< AVar.killVar error

test/Test/Main.purs

@@ -556,7 +556,7 @@ test_avar_order = assert "avar/order" do
     delay (Milliseconds 10.0)
     value ← takeVar var
     modifyRef ref (_ <> value)
-  putVar var "foo"
+  putVar "foo" var
   modifyRef ref (_ <> "taken")
   joinFiber f1
   eq "takenfoo" <$> readRef ref