Limit for number of Tasks running in sequence?

The number of Tasks that can be run in sequence seems to be limited by the max size of the function stack for the platform. Sample code:

import R from 'ramda';
import Task from 'data.task';
import monads from 'control.monads';

const COUNT = 10000;

const l = R.repeat(1, COUNT);

monads.sequence(Task,
                R.map(Task.of, l))
  .fork((err) => console.error(err),
        (res) => console.log(res));

will produce:

/home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:113
  return new Task(function(reject, resolve) {
                          ^

RangeError: Maximum call stack size exceeded
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:113:27
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12
    at /home/francisco/Documents/code/folktale/node_modules/data.task/lib/task.js:114:12

[Avaq]

@robotlolita It doesn’t use free monads directly, but the same principal. Every operation just builds up a structure (much resembling an AST) and fork is the interpreter of that structure.

fork uses the same trick that is used in ChainRec implementations, where everything is executed in a single while-loop that only breaks when the operation did not call back synchronously.

The second trick is the flattening of newly encountered AST’s. When we call a chain, for example, we (lazily) get back a new AST, which is flattened into the current one at runtime, allowing the while-loop to continue without having to break. This part makes it so even recursion is stack safe.

[Avaq]

Fluture implements ChainRec

Not just that. Almost all operations in Fluture are stack safe. ChainRec is really just there for interoperability. Just try to run the exact same code given above but using Fluture:

const R = require('ramda');
const Future = require('fluture');
const monads = require('control.monads');

const COUNT = 1000000; //I increased the number a little to make sure

const l = R.repeat(1, COUNT);

monads.sequence(Future,
                R.map(Future.of, l))
  .fork((err) => console.error(err),
        (res) => console.log(res));

On my i5 machine, after 2.8 seconds, we see:

[1,
 1,
 1,
 ...,
 1,
 1,
 ... 999900 more items]

This all happened in the same tick we called fork.