jet-stream

This is yet another streaming library for Haskell, created to scratch the following itches:

• The main type is as simple as possible: the only type parameter is the type of the yielded elements.

• The Monoid / Alternative / MonadPlus methods perform concatenation, just like with regular lists. The Functor Applicative and Monad instances also resemble those of lists.

• There are direct analogues of functions like withFile, bracket, finally and onError that easy to integrate in a streaming pipeline, and behave smartly when combined with functions like take.

• Compatible with the foldl library for collector-like terminal operations. (All self-respecting streaming libraries must have this.)

In order to achieve those objectives, the following sacrifices have been made:

• No flexibility in the underlying monad for the stream effects: it's always IO.

• No separate "channels" that return extra information at the end of the stream. This means exceptions are the only way of signalling errors or unexpected conditions.

• Elements in a stream can't be "extracted" one by one in a pull-based way, like you can do for example in streaming.

• There's take and drop, but not at proper splitAt. Also, grouping operations are cumbersome and underpowered, especially compared to libraries like streaming or streaming-bytestring.

What about performance?

I haven't run any benchmarks, but you can safely assume that this library will move like a snail compared to streamly's Ferrari.

Some close cousins

• turtle. The Shell type resembles Jet. One possible difference is that Shell doesn't seem to provide a way for the Shell consumer to signal that no further values are needed, at least judging from the docs for limit.

  "turtle" also inspired the idea of having a separate type for lines.

• streamly. I might have reinvented a subset of streamly (but worse).

• Z.IO.BIO from Z-IO. Like Jet, uses a callback-transformation approach.

• The Stream type from Java is somewhat similar to this library's Jet. (And the foldl library would be the analogue of Collectors.)