transducers.drop(n) not working as expected

[threepointone]

import csp, {go, chan} from 'js-csp';
let {fromColl, into, pipeline} = csp.operations;
import xd from 'transducers.js';

// the regular transducer works fine
console.log(xd.seq([1, 2, 3, 4, 5], xd.drop(2)))
// outputs [3, 4, 5]

// but not when used with a channel
go(function*(){
  var c = chan();
  pipeline(c, xd.drop(2), fromColl([1, 2, 3, 4, 5]));
  var res = yield into([], c);  
  console.log(res);
  // expected - [3, 4, 5]
  // actual - []
})

[threepointone]

not sure if related, but dedupe() doesn't work either.

console.log(xd.seq([1, 1, 1, 2, 2, 3, 4, 5, 5, 5, 5, 5, 6, 7], xd.dedupe()))
// as expected - [ 1, 2, 3, 4, 5, 6, 7 ]

go(function*(){
  var c = chan(7);
  pipeline(c, xd.dedupe(), fromColl([1, 1, 1, 2, 2, 3, 4, 5, 5, 5, 5, 5, 6, 7]));
  var res = yield into([], c);  
  console.log(res);
  // - expected - [ 1, 2, 3, 4, 5, 6, 7 ]
  // - actual - [ 1, 1, 1, 2, 2, 3, 4, 5, 5, 5, 5, 5, 6, 7 ]
})

[ubolonton]

Seems to be a pipeline bug. Attaching transducers directly to channels works.
I'm checking it.

[ubolonton]

Actually that's how pipeline is "supposed" to work: applying the transformation to individual items.

In Clojure it's useful for parallelization of non-stateful transformations. In single-threaded js runtimes it's actually quite useless.

[ubolonton]

We need to do the following

• Update the doc to make it clear that pipelineAsync is for parallelism.
• Remove pipeline or fix its doc.
• Maybe augment pipe for the use case of "connecting 2 existing channels via a transducer" (if the code is in control of either channel, it can just attach the transducer when creating the channel).

[threepointone]

ah, I see what you're saying. I worked around it by passing a transducer to the created channel. thanks much.