chore: prepare v1.6.0

README.md

@@ -2,41 +2,114 @@
 
 Interact with node streams in object mode using [`Pipes`]!
 
-## Example
+## Install
-```purescript
-import Prelude
-
-import Effect.Aff (launchAff_)
-import Effect (Effect)
-import Effect.Class (liftEffect)
-import Effect.Console (log)
-import Pipes.Prelude ((>->))
-import Pipes.Prelude as Pipes
-import Pipes.Core as Pipes.Core
-import Pipes.Node.FS.Stream as FS
-import Pipes.Node.Zlib as Zlib
-import Pipes.CSV.Parse as CSV.Parse
-
--- == my-zipped-data.csv ==
--- id,foo,is_deleted
--- 1,hello,f
--- 2,goodbye,t
-
--- Logs:
--- {id: 1, foo: "hello", is_deleted: false}
--- {id: 2, foo: "goodbye", is_deleted: true}
-main :: Effect Unit
-main =
-  Pipes.Core.runEffect
-    $ FS.createReadStream "my-zipped-data.csv.gz"
-        >-> Zlib.gunzip
-        >-> CSV.Parse.parse @{id :: Int, foo :: String, is_deleted :: Boolean}
-        >-> Pipes.mapM (liftEffect <<< log)
-```
-
-## Installing
 ```bash
 spago install node-stream-pipes
 ```
 
+## Usage
+### Node Streams
+#### Raw Streams
+Raw `objectMode` Node streams are represented in `Node.Stream.Object`:
+ - `Writable a` accepts chunks of type `a`
+ - `Readable a` emits chunks of type `a`
+ - `Transform a b` transforms chunks from `a` to `b`
+
+Non-Object streams can also be represented with these types; for example an `fs.WriteStream`
+can be coerced to `Writable Buffer` without issue.
+
+Interop between these types and `Node.Stream` are provided in `Node.Stream.Object`:
+- `unsafeFrom{String,Buffer}{Writable,Readable,Transform}`
+- `unsafeCoerce{Writable,Readable,Transform}`
+
+#### Pipes
+Streams in `Node.Stream.Object` can be converted to `Producer`s, `Consumer`s and `Pipe`s with `Pipes.Node.Stream`:
+ - `fromReadable :: forall a. <Readable a> -> Producer (Maybe a) <Aff> Unit`
+ - `fromWritable :: forall a. <Writable a> -> Consumer (Maybe a) <Aff> Unit`
+ - `fromTransform :: forall a b. <Transform a b> -> Pipe (Maybe a) (Maybe b) <Aff> Unit`
+
+#### EOS Marker
+Normally, pipe computations will not be executed once any computation in a pipeline exits.
+
+To allow for resource cleanup and awareness that the stream is about to close,
+`Maybe a` is used occasionally in this package as an End-of-Stream marker:
+
+```purescript
+-- foo.txt is "hello, world!\n"
+chunks <- Pipes.Collect.toArray $ Pipes.FS.read "foo.txt" >-> Pipes.Node.Stream.inEOS (Pipes.Buffer.toString UTF8)
+chunks `shouldEqual` [Just "hello, world!\n", Nothing]
+```
+
+Pipes from `a -> b` unaware of EOS can be lifted to `Maybe a -> Maybe b` with `Pipes.Node.Stream.inEOS`.
+
+Producers of `Maybe a` can drop the EOS marker and emit `a` with `Pipes.Node.Stream.unEOS`.
+
+Producers of `a` can have an EOS marker added with `Pipes.Node.Stream.withEOS`.
+
+#### Example
+`Pipes.PassThrough.js`
+```javascript
+import {PassThrough} from 'stream'
+
+export const makePassThrough = () => new PassThrough()
+```
+
+`Pipes.PassThrough.purs`
+```purescript
+module Pipes.PassThrough where
+
+import Prelude
+
+import Effect (Effect)
+import Effect.Class (liftEffect)
+import Effect.Aff (Aff)
+import Pipes.Core (Pipe)
+import Node.Stream.Object as ObjectStream
+import Pipes.Node.Stream as Pipes.Node.Stream
+
+type PassThroughStream a = ObjectStream.Transform a a
+
+foreign import makeRaw :: Effect PassThroughStream
+
+passThrough :: forall a. Pipe a a Aff Unit
+passThrough = do
+  raw <- liftEffect $ makeRaw
+  Pipes.Node.Stream.fromTransform raw
+```
+
+### Utilities
+This package provides utilities that explicitly use `MonadRec` to ensure stack-safety
+when dealing with producers of large amounts of data.
+
+- `Pipes.Collect` provides stack-safe utilities for executing a pipeline and collecting results into a collection, `Buffer`, `Monoid` etc.
+- `Pipes.Construct` provides stack-safe utilities for creating producers from in-memory collections.
+- `Pipes.Util` provides some miscellaneous utilities missing from `pipes`.
+
+### Zlib
+Pipes for compression & decompression using `zlib` are provided in `Pipes.Node.Zlib`.
+
+### FS
+Read files with:
+- `Pipes.Node.FS.read <path>`
+- `Pipes.Node.FS.read' <WriteStreamOptions> <path>`
+
+```purescript
+Pipes.Collect.toStringWith UTF8 $ Pipes.Node.FS.read "foo.txt" >-> Pipes.Stream.unEOS
+```
+
+Write files with:
+ - `Pipes.Node.FS.write' <WriteStreamOptions> <path>`
+ - `Pipes.Node.FS.trunc <path>`
+ - `Pipes.Node.FS.create <path>`
+ - `Pipes.Node.FS.append <path>`
+
+```purescript
+  Pipes.Stream.withEOS (
+    Pipes.Construct.eachArray ["id,name", "1,henry", "2,suzie"]
+    >-> Pipes.Util.intersperse "\n"
+    >-> Pipes.Buffer.fromString UTF8
+  )
+  >-> Pipes.Node.FS.create "foo.csv"
+```
+
 [`Pipes`]: https://pursuit.purescript.org/packages/purescript-pipes/8.0.0

package.json

@@ -1,6 +1,6 @@
 {
   "name": "purescript-node-stream-pipes",
-  "version": "v1.4.0",
+  "version": "v1.6.0",
   "type": "module",
   "dependencies": {
     "csv-parse": "^5.5.5",

spago.lock

@@ -13,7 +13,6 @@ workspace:
         - lists: ">=7.0.0 <8.0.0"
         - maybe: ">=6.0.0 <7.0.0"
         - mmorph: ">=7.0.0 <8.0.0"
-        - newtype: ">=5.0.0 <6.0.0"
         - node-buffer: ">=9.0.0 <10.0.0"
         - node-event-emitter: ">=3.0.0 <4.0.0"
         - node-fs: ">=9.1.0 <10.0.0"

spago.yaml

@@ -1,7 +1,7 @@
 package:
   name: node-stream-pipes
   publish:
-    version: '1.4.0'
+    version: '1.6.0'
     license: 'GPL-3.0-or-later'
     location:
       githubOwner: 'cakekindel'
@@ -20,7 +20,6 @@ package:
     - lists: ">=7.0.0 <8.0.0"
     - maybe: ">=6.0.0 <7.0.0"
     - mmorph: ">=7.0.0 <8.0.0"
-    - newtype: ">=5.0.0 <6.0.0"
     - node-buffer: ">=9.0.0 <10.0.0"
     - node-event-emitter: ">=3.0.0 <4.0.0"
     - node-fs: ">=9.1.0 <10.0.0"

src/Node.Stream.Object.js

@@ -21,19 +21,18 @@ export const isReadableEndedImpl = (s) => () => s.readableEnded;
 /** @type {(s: Stream.Writable | Stream.Transform) => () => boolean} */
 export const isWritableEndedImpl = (s) => () => s.writableEnded;
 
+/** @type {(s: Stream.Writable | Stream.Transform) => () => boolean} */
+export const isWritableFinishedImpl = (s) => () => s.writableFinished;
+
 /** @type {(s: Stream.Writable | Stream.Transform) => () => void} */
 export const endImpl = (s) => () => s.end();
 
-/** @type {<WriteResult>(o: {ok: WriteResult, wouldBlock: WriteResult, closed: WriteResult}) => (s: Stream.Writable | Stream.Transform) => (a: unknown) => () => WriteResult} */
+/** @type {<WriteResult>(o: {ok: WriteResult, wouldBlock: WriteResult}) => (s: Stream.Writable | Stream.Transform) => (a: unknown) => () => WriteResult} */
 export const writeImpl =
-  ({ ok, wouldBlock, closed }) =>
+  ({ ok, wouldBlock }) =>
   (s) =>
   (a) =>
   () => {
-    if (s.closed || s.writableEnded) {
-      return closed;
-    }
-
     if (s.write(a)) {
       return ok;
     } else {
@@ -41,15 +40,11 @@ export const writeImpl =
     }
   };
 
-/** @type {<ReadResult>(o: {just: (_a: unknown) => ReadResult, wouldBlock: ReadResult, closed: ReadResult}) => (s: Stream.Readable | Stream.Transform) => () => ReadResult} */
+/** @type {<ReadResult>(o: {just: (_a: unknown) => ReadResult, wouldBlock: ReadResult}) => (s: Stream.Readable | Stream.Transform) => () => ReadResult} */
 export const readImpl =
-  ({ just, closed, wouldBlock }) =>
+  ({ just, wouldBlock }) =>
   (s) =>
   () => {
-    if (s.closed || s.readableEnded) {
-      return closed;
-    }
-
     const a = s.read();
     if (a === null) {
       return wouldBlock;

src/Node.Stream.Object.purs

@@ -14,8 +14,9 @@ import Data.Maybe (Maybe(..))
 import Data.Show.Generic (genericShow)
 import Effect (Effect)
 import Effect.Aff (Aff, effectCanceler, makeAff)
+import Effect.Aff as Aff
 import Effect.Class (liftEffect)
-import Effect.Exception (Error)
+import Effect.Exception (Error, error)
 import Effect.Uncurried (mkEffectFn1)
 import Node.Buffer (Buffer)
 import Node.EventEmitter (EventHandle(..))
@@ -26,7 +27,6 @@ import Unsafe.Coerce (unsafeCoerce)
 
 data ReadResult a
   = ReadWouldBlock
-  | ReadClosed
   | ReadJust a
 
 derive instance Generic (ReadResult a) _
@@ -35,9 +35,12 @@ derive instance Eq a => Eq (ReadResult a)
 instance Show (ReadResult a) where
   show = genericShow <<< map (const "..")
 
+maybeReadResult :: forall a. ReadResult a -> Maybe a
+maybeReadResult (ReadWouldBlock) = Nothing
+maybeReadResult (ReadJust a) = Just a
+
 data WriteResult
   = WriteWouldBlock
-  | WriteClosed
   | WriteOk
 
 derive instance Generic WriteResult _
@@ -45,8 +48,8 @@ derive instance Eq WriteResult
 instance Show WriteResult where
   show = genericShow
 
-type ReadResultFFI a = { closed :: ReadResult a, wouldBlock :: ReadResult a, just :: a -> ReadResult a }
+type ReadResultFFI a = { wouldBlock :: ReadResult a, just :: a -> ReadResult a }
-type WriteResultFFI = { closed :: WriteResult, wouldBlock :: WriteResult, ok :: WriteResult }
+type WriteResultFFI = { wouldBlock :: WriteResult, ok :: WriteResult }
 
 foreign import data Writable :: Type -> Type
 foreign import data Readable :: Type -> Type
@@ -59,15 +62,16 @@ foreign import isReadableImpl :: forall s. s -> Effect Boolean
 foreign import isWritableImpl :: forall s. s -> Effect Boolean
 foreign import isReadableEndedImpl :: forall s. s -> Effect Boolean
 foreign import isWritableEndedImpl :: forall s. s -> Effect Boolean
+foreign import isWritableFinishedImpl :: forall s. s -> Effect Boolean
 foreign import isClosedImpl :: forall s. s -> Effect Boolean
 foreign import needsDrainImpl :: forall s. s -> Effect Boolean
 foreign import readableLengthImpl :: forall s. s -> Effect Int
 
 readResultFFI :: forall a. ReadResultFFI a
-readResultFFI = { closed: ReadClosed, wouldBlock: ReadWouldBlock, just: ReadJust }
+readResultFFI = { wouldBlock: ReadWouldBlock, just: ReadJust }
 
 writeResultFFI :: WriteResultFFI
-writeResultFFI = { closed: WriteClosed, wouldBlock: WriteWouldBlock, ok: WriteOk }
+writeResultFFI = { wouldBlock: WriteWouldBlock, ok: WriteOk }
 
 class Stream :: Type -> Constraint
 class Stream s where
@@ -92,6 +96,7 @@ class Stream s <= Write s a | s -> a where
   isWritable :: s -> Effect Boolean
   needsDrain :: s -> Effect Boolean
   isWritableEnded :: s -> Effect Boolean
+  isWritableFinished :: s -> Effect Boolean
   write :: s -> a -> Effect WriteResult
   end :: s -> Effect Unit
 
@@ -114,18 +119,21 @@ else instance (Read s a) => Read s a where
 instance Write (Writable a) a where
   isWritable = isWritableImpl
   isWritableEnded = isWritableEndedImpl
+  isWritableFinished = isWritableFinishedImpl
   write s = writeImpl writeResultFFI s
   end = endImpl
   needsDrain = needsDrainImpl
 else instance Write (Transform a b) a where
   isWritable = isWritableImpl
   isWritableEnded = isWritableEndedImpl
+  isWritableFinished = isWritableFinishedImpl
   write s = writeImpl writeResultFFI s
   end = endImpl
   needsDrain = needsDrainImpl
 else instance (Write s a) => Write s a where
   isWritable = isWritableImpl
   isWritableEnded = isWritableEndedImpl
+  isWritableFinished = isWritableFinishedImpl
   write s a = write s a
   end s = end s
   needsDrain = needsDrainImpl
@@ -136,45 +144,67 @@ withErrorST s = do
   cancel <- flip (Event.once errorH) s \e -> void $ liftST $ STRef.write (Just e) error
   pure { error, cancel }
 
-fromBufferReadable :: forall r. Stream.Readable r -> Readable Buffer
+unsafeCoerceWritable :: forall r a. Stream.Writable r -> Writable a
-fromBufferReadable = unsafeCoerce
+unsafeCoerceWritable = unsafeCoerce
 
-fromBufferTransform :: Stream.Duplex -> Transform Buffer Buffer
+unsafeCoerceReadable :: forall r a. Stream.Readable r -> Readable a
-fromBufferTransform = unsafeCoerce
+unsafeCoerceReadable = unsafeCoerce
 
-fromBufferWritable :: forall r. Stream.Writable r -> Writable Buffer
+unsafeCoerceTransform :: forall a b. Stream.Duplex -> Transform a b
-fromBufferWritable = unsafeCoerce
+unsafeCoerceTransform = unsafeCoerce
 
-fromStringReadable :: forall r. Stream.Readable r -> Readable String
+unsafeFromBufferReadable :: forall r. Stream.Readable r -> Readable Buffer
-fromStringReadable = unsafeCoerce
+unsafeFromBufferReadable = unsafeCoerce
 
-fromStringTransform :: Stream.Duplex -> Transform String String
+unsafeFromBufferTransform :: forall a. Stream.Duplex -> Transform Buffer a
-fromStringTransform = unsafeCoerce
+unsafeFromBufferTransform = unsafeCoerce
 
-fromStringWritable :: forall r. Stream.Writable r -> Writable String
+unsafeFromBufferWritable :: forall r. Stream.Writable r -> Writable Buffer
-fromStringWritable = unsafeCoerce
+unsafeFromBufferWritable = unsafeCoerce
+
+unsafeFromStringReadable :: forall r. Stream.Readable r -> Readable String
+unsafeFromStringReadable = unsafeCoerce
+
+unsafeFromStringTransform :: forall a. Stream.Duplex -> Transform String a
+unsafeFromStringTransform = unsafeCoerce
+
+unsafeFromStringWritable :: forall r. Stream.Writable r -> Writable String
+unsafeFromStringWritable = unsafeCoerce
 
 awaitReadableOrClosed :: forall s a. Read s a => s -> Aff Unit
 awaitReadableOrClosed s = do
+  fiber <-
+    Aff.forkAff $ parOneOf
+      [ onceAff0 readableH s $> Right unit
+      , onceAff0 closeH s $> Right unit
+      , Left <$> onceAff1 errorH s
+      ]
+  closed <- liftEffect $ isClosed s
+  readEnded <- liftEffect $ isReadableEnded s
   readable <- liftEffect $ isReadable s
   length <- liftEffect $ readableLength s
-  when (readable && length == 0)
+  if (not closed && not readEnded && readable && length == 0) then
-    $ liftEither
+    liftEither =<< Aff.joinFiber fiber
-        =<< parOneOf
+  else
-          [ onceAff0 readableH s $> Right unit
+    Aff.killFiber (error "") fiber
-          , onceAff0 closeH s $> Right unit
-          , Left <$> onceAff1 errorH s
-          ]
 
 awaitFinished :: forall s a. Write s a => s -> Aff Unit
-awaitFinished s = onceAff0 finishH s
+awaitFinished s = do
+  fiber <- Aff.forkAff $ onceAff0 finishH s
+  finished <- liftEffect $ isWritableFinished s
+  if not finished then Aff.joinFiber fiber else Aff.killFiber (error "") fiber
 
 awaitWritableOrClosed :: forall s a. Write s a => s -> Aff Unit
 awaitWritableOrClosed s = do
+  fiber <- Aff.forkAff $ parOneOf [ onceAff0 drainH s $> Right unit, onceAff0 closeH s $> Right unit, Left <$> onceAff1 errorH s ]
+  closed <- liftEffect $ isClosed s
+  writeEnded <- liftEffect $ isWritableEnded s
   writable <- liftEffect $ isWritable s
   needsDrain <- liftEffect $ needsDrain s
-  when (writable && needsDrain)
+  if not closed && not writeEnded && writable && needsDrain then
-    $ liftEither =<< parOneOf [ onceAff0 drainH s $> Right unit, onceAff0 closeH s $> Right unit, Left <$> onceAff1 errorH s ]
+    liftEither =<< Aff.joinFiber fiber
+  else
+    Aff.killFiber (error "") fiber
 
 onceAff0 :: forall e. EventHandle0 e -> e -> Aff Unit
 onceAff0 h emitter = makeAff \res -> do

src/Pipes.Collect.purs

@@ -20,6 +20,7 @@ import Foreign.Object.ST as Object.ST
 import Foreign.Object.ST.Unsafe as Object.ST.Unsafe
 import Node.Buffer (Buffer)
 import Node.Buffer as Buffer
+import Node.Encoding (Encoding)
 import Pipes.Core (Producer)
 import Pipes.Internal (Proxy(..))
 
@@ -51,7 +52,16 @@ fold f b0 p0 = traverse (\b a -> pure $ f b a) b0 p0
 foreach :: forall a m. MonadRec m => (a -> m Unit) -> Producer a m Unit -> m Unit
 foreach f p0 = traverse (\_ a -> f a) unit p0
 
--- | Concatenate all produced buffers
+-- | `append` all emitted values to `mempty`
+toMonoid :: forall a m. Monoid a => MonadRec m => MonadEffect m => Producer a m Unit -> m a
+toMonoid = fold (<>) mempty
+
+-- | Concatenate all buffers to a single buffer, then decode with the
+-- | provided encoding.
+toStringWith :: forall m. MonadRec m => MonadEffect m => Encoding -> Producer Buffer m Unit -> m String
+toStringWith enc = (liftEffect <<< Buffer.toString enc) <=< toBuffer
+
+-- | Concatenate all produced buffers to a single buffer
 toBuffer :: forall m. MonadRec m => MonadEffect m => Producer Buffer m Unit -> m Buffer
 toBuffer p =
   (liftEffect <<< maybe (Buffer.alloc 0) pure)
@@ -74,9 +84,18 @@ toArray p = do
   liftEffect $ liftST $ Array.ST.unsafeFreeze st
 
 -- | Collect all values from a `Producer` into a list.
+-- |
+-- | Reverses the list after collecting, so that values will be
+-- | in the order they were emitted.
 toList :: forall a m. MonadRec m => MonadEffect m => Producer a m Unit -> m (List a)
 toList = map List.reverse <<< fold (flip List.Cons) List.Nil
 
+-- | Collect all values from a `Producer` into a list.
+-- |
+-- | Does not reverse the list after collecting.
+toListRev :: forall a m. MonadRec m => MonadEffect m => Producer a m Unit -> m (List a)
+toListRev = map List.reverse <<< fold (flip List.Cons) List.Nil
+
 -- | Collect all values from a `Producer` into a Javascript Object.
 toObject :: forall a m. MonadRec m => MonadEffect m => Producer (String /\ a) m Unit -> m (Object a)
 toObject p = do

src/Pipes.Node.FS.purs

@@ -23,7 +23,7 @@ import Prim.Row (class Union)
 -- |
 -- | See `Pipes.Node.Stream.withEOS` for converting `Producer a`
 -- | into `Producer (Maybe a)`, emitting `Nothing` before exiting.
-write
+write'
   :: forall r trash m
    . Union r trash WriteStreamOptions
   => MonadAff m
@@ -31,27 +31,27 @@ write
   => Record r
   -> FilePath
   -> Consumer (Maybe Buffer) m Unit
-write o p = do
+write' o p = do
   w <- liftEffect $ FS.Stream.createWriteStream' p o
-  fromWritable $ O.fromBufferWritable w
+  fromWritable $ O.unsafeCoerceWritable w
 
 -- | Open a file in write mode, failing if the file already exists.
 -- |
--- | `write {flags: "wx"}`
+-- | `write' {flags: "wx"}`
 create :: forall m. MonadAff m => MonadThrow Error m => FilePath -> Consumer (Maybe Buffer) m Unit
-create = write { flags: "wx" }
+create = write' { flags: "wx" }
 
 -- | Open a file in write mode, truncating it if the file already exists.
 -- |
--- | `write {flags: "w"}`
+-- | `write' {flags: "w"}`
-truncate :: forall m. MonadAff m => MonadThrow Error m => FilePath -> Consumer (Maybe Buffer) m Unit
+trunc :: forall m. MonadAff m => MonadThrow Error m => FilePath -> Consumer (Maybe Buffer) m Unit
-truncate = write { flags: "w" }
+trunc = write' { flags: "w" }
 
 -- | Open a file in write mode, appending written contents if the file already exists.
 -- |
--- | `write {flags: "a"}`
+-- | `write' {flags: "a"}`
 append :: forall m. MonadAff m => MonadThrow Error m => FilePath -> Consumer (Maybe Buffer) m Unit
-append = write { flags: "a" }
+append = write' { flags: "a" }
 
 -- | Creates a `fs.Readable` stream for the file at the given path.
 -- |
@@ -60,7 +60,7 @@ append = write { flags: "a" }
 read :: forall m. MonadAff m => MonadThrow Error m => FilePath -> Producer (Maybe Buffer) m Unit
 read p = do
   r <- liftEffect $ FS.Stream.createReadStream p
-  fromReadable $ O.fromBufferReadable r
+  fromReadable $ O.unsafeCoerceReadable r
 
 -- | Creates a `fs.Readable` stream for the file at the given path.
 -- |
@@ -76,4 +76,4 @@ read'
   -> Producer (Maybe Buffer) m Unit
 read' opts p = do
   r <- liftEffect $ FS.Stream.createReadStream' p opts
-  fromReadable $ O.fromBufferReadable r
+  fromReadable $ O.unsafeCoerceReadable r

src/Pipes.Node.Stream.purs

@@ -3,15 +3,13 @@ module Pipes.Node.Stream where
 import Prelude hiding (join)
 
 import Control.Monad.Error.Class (class MonadThrow, throwError)
-import Control.Monad.Rec.Class (class MonadRec, Step(..), tailRecM)
+import Control.Monad.Rec.Class (class MonadRec, Step(..), tailRecM, whileJust)
 import Control.Monad.ST.Class (liftST)
 import Control.Monad.ST.Ref as STRef
 import Control.Monad.Trans.Class (lift)
-import Data.Maybe (Maybe(..))
+import Data.Maybe (Maybe(..), maybe)
-import Data.Newtype (wrap)
+import Data.Traversable (for_, traverse, traverse_)
-import Data.Traversable (for_)
 import Data.Tuple.Nested ((/\))
-import Effect.Aff (delay)
 import Effect.Aff.Class (class MonadAff, liftAff)
 import Effect.Class (liftEffect)
 import Effect.Exception (Error)
@@ -19,7 +17,6 @@ import Node.Stream.Object as O
 import Pipes (await, yield)
 import Pipes (for) as P
 import Pipes.Core (Consumer, Pipe, Producer, Producer_)
-import Pipes.Prelude (mapFoldable) as P
 import Pipes.Util (InvokeResult(..), invoke)
 
 -- | Convert a `Readable` stream to a `Pipe`.
@@ -40,8 +37,13 @@ fromReadable r =
       res <- liftEffect $ O.read r
       case res of
         O.ReadJust a -> yield (Just a) $> Loop { error, cancel }
-        O.ReadWouldBlock -> liftAff (O.awaitReadableOrClosed r) $> Loop { error, cancel }
+        O.ReadWouldBlock -> do
-        O.ReadClosed -> yield Nothing *> cleanup cancel
+          ended <- liftEffect $ O.isReadableEnded r
+          if ended then do
+            yield Nothing
+            cleanup cancel
+          else
+            liftAff (O.awaitReadableOrClosed r) $> Loop { error, cancel }
   in
     do
       e <- liftEffect $ O.withErrorST r
@@ -52,86 +54,78 @@ fromReadable r =
 -- | When `Nothing` is piped to this, the stream will
 -- | be `end`ed, and the pipe will noop if invoked again.
 fromWritable :: forall s a m. MonadThrow Error m => MonadAff m => O.Write s a => s -> Consumer (Maybe a) m Unit
-fromWritable w =
+fromWritable w = do
+  { error: errorST, cancel: removeErrorListener } <- liftEffect $ O.withErrorST w
+
   let
-    cleanup rmErrorListener = do
+    maybeThrow = traverse_ throwError =<< liftEffect (liftST $ STRef.read errorST)
-      liftEffect rmErrorListener
+
-      liftEffect $ O.end w
+    waitCanWrite = do
+      shouldWait <- liftEffect $ O.needsDrain w
+      when shouldWait $ liftAff $ O.awaitWritableOrClosed w
+
+    cleanup = do
       liftAff $ O.awaitFinished w
-      pure $ Done unit
+      maybeThrow
+      liftEffect removeErrorListener
 
-    go { error, cancel } = do
+    onEOS = liftEffect (O.end w) *> cleanup $> Done unit
-      err <- liftEffect $ liftST $ STRef.read error
+    onChunk a = liftEffect (O.write w a) $> Loop unit
-      for_ err throwError
 
-      needsDrain <- liftEffect $ O.needsDrain w
+    go _ = do
-      when needsDrain $ liftAff $ O.awaitWritableOrClosed w
+      maybeThrow
-      ma <- await
+      waitCanWrite
-      case ma of
+      ended <- liftEffect $ O.isWritableEnded w
-        Nothing -> cleanup cancel
+      if ended then
-        Just a -> do
+        cleanup $> Done unit
-          res <- liftEffect $ O.write w a
+      else
-          case res of
+        await >>= maybe onEOS onChunk
-            O.WriteClosed -> cleanup cancel
+
-            _ -> pure $ Loop { error, cancel }
+  tailRecM go unit
-  in
-    do
-      r <- liftEffect $ O.withErrorST w
-      tailRecM go r
 
 -- | Convert a `Transform` stream to a `Pipe`.
 -- |
 -- | When `Nothing` is piped to this, the `Transform` stream will
 -- | be `end`ed, and the pipe will noop if invoked again.
 fromTransform :: forall a b m. MonadThrow Error m => MonadAff m => O.Transform a b -> Pipe (Maybe a) (Maybe b) m Unit
-fromTransform t =
+fromTransform t = do
+  { error: errorST, cancel: removeErrorListener } <- liftEffect $ O.withErrorST t
   let
-    cleanup removeErrorListener = do
+    maybeThrow = traverse_ throwError =<< liftEffect (liftST $ STRef.read errorST)
-      liftEffect $ O.end t
-      liftEffect $ removeErrorListener
-      fromReadable t
-      pure $ Done unit
 
-    yieldWhileReadable = do
+    cleanup = do
-      flip tailRecM unit \_ -> do
+      flip tailRecM unit $ const do
-        res <- liftEffect $ O.read t
+        liftAff $ O.awaitReadableOrClosed t
-        case res of
+        readEnded <- liftEffect $ O.isReadableEnded t
-          O.ReadJust a -> yield (Just a) $> Loop unit
-          _ -> pure $ Done unit
-
-    maybeYield1 = do
-      res <- liftEffect $ O.read t
-      case res of
-        O.ReadJust a -> yield $ Just a
-        _ -> pure unit
-
-    go { error, cancel } = do
-      err <- liftEffect $ liftST $ STRef.read error
-      for_ err throwError
-
-      needsDrain <- liftEffect $ O.needsDrain t
-      if needsDrain then do
-        liftAff $ delay $ wrap 0.0
         yieldWhileReadable
-        pure $ Loop { error, cancel }
+        pure $ (if readEnded then Done else Loop) unit
-      else do
+
-        ma <- await
+      liftAff $ O.awaitFinished t
-        case ma of
+      maybeThrow
-          Nothing -> cleanup cancel
+      liftEffect $ removeErrorListener
-          Just a' -> do
+      yield Nothing
-            res <- liftEffect $ O.write t a'
+
-            case res of
+    yieldWhileReadable = void $ whileJust $ maybeYield1
-              O.WriteClosed -> cleanup cancel
+
-              O.WriteOk -> do
+    maybeYield1 = traverse (\a -> yield (Just a) $> Just unit) =<< O.maybeReadResult <$> liftEffect (O.read t)
-                maybeYield1
+
-                pure $ Loop { error, cancel }
+    onEOS = liftEffect (O.end t) *> cleanup $> Done unit
-              O.WriteWouldBlock -> do
+    onChunk a = liftEffect (O.write t a) $> Loop unit
-                yieldWhileReadable
+
-                pure $ Loop { error, cancel }
+    go _ = do
-  in
+      maybeThrow
-    do
+      needsDrain <- liftEffect $ O.needsDrain t
-      r <- liftEffect $ O.withErrorST t
+      ended <- liftEffect $ O.isWritableEnded t
-      tailRecM go r
+      if needsDrain then do
+        yieldWhileReadable
+        liftAff $ O.awaitWritableOrClosed t
+        pure $ Loop unit
+      else if ended then
+        cleanup $> Done unit
+      else
+        await >>= maybe onEOS onChunk
+
+  tailRecM go unit
 
 -- | Given a `Producer` of values, wrap them in `Just`.
 -- |
@@ -143,7 +137,7 @@ withEOS a = do
 
 -- | Strip a pipeline of the EOS signal
 unEOS :: forall a m. Monad m => Pipe (Maybe a) a m Unit
-unEOS = P.mapFoldable identity
+unEOS = tailRecM (const $ maybe (pure $ Done unit) (\a -> yield a $> Loop unit) =<< await) unit
 
 -- | Lift a `Pipe a a` to `Pipe (Maybe a) (Maybe a)`.
 -- |

src/Pipes.Node.Zlib.purs

@@ -18,7 +18,7 @@ import Pipes.Node.Stream (fromTransform)
 fromZlib :: forall r m. MonadAff m => MonadThrow Error m => Effect (ZlibStream r) -> Pipe (Maybe Buffer) (Maybe Buffer) m Unit
 fromZlib z = do
   raw <- liftEffect $ Zlib.toDuplex <$> z
-  fromTransform $ O.fromBufferTransform raw
+  fromTransform $ O.unsafeCoerceTransform raw
 
 gzip :: forall m. MonadAff m => MonadThrow Error m => Pipe (Maybe Buffer) (Maybe Buffer) m Unit
 gzip = fromZlib Zlib.createGzip

src/Pipes.Util.purs

@@ -86,9 +86,14 @@ chunked size = do
     a <- MaybeT await
     chunkPut a
     len <- lift chunkLength
-    when (len >= size) $ lift $ yield =<< Just <$> chunkTake
+    when (len >= size) do
+      chunk <- lift chunkTake
+      lift $ yield $ Just chunk
   len <- chunkLength
-  when (len > 0) $ yield =<< Just <$> chunkTake
+  when (len > 0) do
+    chunk <- chunkTake
+    yield $ Just chunk
+
   yield Nothing
 
 -- | Equivalent of unix `uniq`, filtering out duplicate values passed to it.

test/Test/Pipes.Node.FS.purs

@@ -33,11 +33,6 @@ spec = describe "Pipes.Node.FS" do
       liftEffect $ FS.writeTextFile UTF8 p "foo"
       s <- fold <$> Pipes.toListM (Pipes.Node.FS.read p >-> unEOS >-> Pipes.Node.Buffer.toString UTF8)
       s `shouldEqual` "foo"
-    around tmpFile $ it "fails if the file already exists" \p -> do
-      liftEffect $ FS.writeTextFile UTF8 p "foo"
-      flip catchError (const $ pure unit) do
-        Pipes.runEffect $ withEOS (yield "foo" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.create p
-        fail "should have thrown"
   describe "create" do
     around tmpFile $ it "creates the file when not exists" \p -> do
       Pipes.runEffect $ withEOS (yield "foo" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.create p
@@ -59,14 +54,14 @@ spec = describe "Pipes.Node.FS" do
       Pipes.runEffect $ withEOS (yield "bar" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.append p
       contents <- liftEffect $ FS.readTextFile UTF8 p
       contents `shouldEqual` "foo\nbar"
-  describe "truncate" do
+  describe "trunc" do
     around tmpFile $ it "creates the file when not exists" \p -> do
-      Pipes.runEffect $ withEOS (yield "foo" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.truncate p
+      Pipes.runEffect $ withEOS (yield "foo" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.trunc p
       contents <- liftEffect $ FS.readTextFile UTF8 p
       contents `shouldEqual` "foo"
     around tmpFile $ it "overwrites contents" \p -> do
-      Pipes.runEffect $ withEOS (yield "foo" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.truncate p
+      Pipes.runEffect $ withEOS (yield "foo" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.trunc p
-      Pipes.runEffect $ withEOS (yield "bar" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.truncate p
+      Pipes.runEffect $ withEOS (yield "bar" >-> Pipes.Node.Buffer.fromString UTF8) >-> Pipes.Node.FS.trunc p
       contents <- liftEffect $ FS.readTextFile UTF8 p
       contents `shouldEqual` "bar"
   around tmpFiles $ it "json lines >-> parse >-> _.foo >-> write" \(a /\ b) -> do

test/Test/Pipes.Node.Stream.purs

@@ -40,11 +40,11 @@ foreign import charsTransform :: Effect (O.Transform String String)
 
 writer :: forall m. MonadEffect m => String -> m (O.Writable Buffer /\ Consumer (Maybe Buffer) Aff Unit)
 writer a = do
-  stream <- liftEffect $ O.fromBufferWritable <$> FS.Stream.createWriteStream a
+  stream <- liftEffect $ O.unsafeCoerceWritable <$> FS.Stream.createWriteStream a
   pure $ stream /\ S.fromWritable stream
 
 reader :: forall m. MonadEffect m => String -> m (Producer (Maybe Buffer) Aff Unit)
-reader a = liftEffect $ S.fromReadable <$> O.fromBufferReadable <$> FS.Stream.createReadStream a
+reader a = liftEffect $ S.fromReadable <$> O.unsafeCoerceReadable <$> FS.Stream.createReadStream a
 
 spec :: Spec Unit
 spec =
@@ -64,7 +64,7 @@ spec =
     describe "Writable" $ around tmpFile do
       describe "fs.WriteStream" do
         it "pipe to file" \p -> do
-          stream <- O.fromBufferWritable <$> liftEffect (FS.Stream.createWriteStream p)
+          stream <- O.unsafeCoerceWritable <$> liftEffect (FS.Stream.createWriteStream p)
           let
             w = S.fromWritable stream
             source = do
@@ -75,7 +75,7 @@ spec =
           contents `shouldEqual` "hello"
           shouldEqual true =<< liftEffect (O.isWritableEnded stream)
         it "async pipe to file" \p -> do
-          w <- S.fromWritable <$> O.fromBufferWritable <$> liftEffect (FS.Stream.createWriteStream p)
+          w <- S.fromWritable <$> O.unsafeCoerceWritable <$> liftEffect (FS.Stream.createWriteStream p)
           let
             source = do
               yield "hello, "
@@ -110,7 +110,7 @@ spec =
         let
           json = yield $ writeJSON { foo: "bar" }
           exp = "1f8b0800000000000003ab564acbcf57b2524a4a2c52aa0500eff52bfe0d000000"
-        gzip <- S.fromTransform <$> O.fromBufferTransform <$> liftEffect (Zlib.toDuplex <$> Zlib.createGzip)
+        gzip <- S.fromTransform <$> O.unsafeCoerceTransform <$> liftEffect (Zlib.toDuplex <$> Zlib.createGzip)
         outs :: List.List String <- Pipes.toListM (S.withEOS (json >-> Pipes.Buffer.fromString UTF8) >-> gzip >-> S.unEOS >-> Pipes.Buffer.toString Hex)
         fold outs `shouldEqual` exp
       around tmpFiles
@@ -118,11 +118,11 @@ spec =
             liftEffect $ FS.writeTextFile UTF8 a $ writeJSON [ 1, 2, 3, 4 ]
             areader <- liftEffect $ reader a
             bwritestream /\ bwriter <- liftEffect $ writer b
-            gzip <- S.fromTransform <$> O.fromBufferTransform <$> liftEffect (Zlib.toDuplex <$> Zlib.createGzip)
+            gzip <- S.fromTransform <$> O.unsafeCoerceTransform <$> liftEffect (Zlib.toDuplex <$> Zlib.createGzip)
             runEffect $ areader >-> gzip >-> bwriter
             shouldEqual true =<< liftEffect (O.isWritableEnded bwritestream)
 
-            gunzip <- S.fromTransform <$> O.fromBufferTransform <$> liftEffect (Zlib.toDuplex <$> Zlib.createGunzip)
+            gunzip <- S.fromTransform <$> O.unsafeCoerceTransform <$> liftEffect (Zlib.toDuplex <$> Zlib.createGunzip)
             breader <- liftEffect $ reader b
             nums <- Pipes.toListM (breader >-> gunzip >-> S.unEOS >-> Pipes.Buffer.toString UTF8 >-> jsonParse @(Array Int) >-> Pipes.mapFoldable identity)
             Array.fromFoldable nums `shouldEqual` [ 1, 2, 3, 4 ]