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Changelog

Version 4.0.1

Date: 2019-10-03

Minor code simplication
cljdoc integration

Version 4.0.0

Date: 2019-10-01

Relevant changes (many breaking changes that affects functions and macros that are not heavily used):

Remove the ability to create a promise using factory function with promise constructor (now this responsability is delegated to the create function, see below).
Remove the old do* macro.
Add do! macro (that should have been the do* from the begining). It treats each individual expression as a expression that evaluates to promise and executes serially awaiting each expression. Returns a promise resolved to the result of the last expression, ignoring all intermediate results.

(require '[promesa.core :as p])

(p/do! (expr1)
       (expr2)
       (expr3))

;; That is roughtly equivalent to:

(p/alet [_ (expr1)
         _ (expr2)]
  (expr3))

Refactor execution strategy: before this change all the chained callback functions (with map, then, etc..) they were running in a separated (async) microtask (forkJoinPool on the jvm). Now promesa does not makes any asumption about this and delegate this decision to the user of this library.

What are the implications for the end user?: In terms of api changes, nothing; all the public api is the same. The main change consists in the execution semantics. Now all the chained functions (by default) will be executed in the calling/resolver thread instead of a new task for each step. This will leverage a better performance and less latency on all chain execution.

Also, promesa exposes additional arities to map, then, bind and mapcat for provide a custom executor service if you need it.

The promise and deferred (read more below) promise constructors also accepts a new arity for specify the executor where evaluate the factory function or promise resolution (by default is in the calling thread).

The execution semantic changes are only relevant on the JVM, on cljs nothing is changed.
Rewrite finally function: now receives a promise and a function (potentiall side-effectful) that will receive resolved value as first argument if the promise is resolved or exception as second argument if promise is rejected. The return value is ignored. It always returns the same promise (like identity function).
Remove 0 arity from promise function (now is delegated to deferred)
Remove schedule function from promesa.core (replaced by promesa.exec/schedule).
Remove extend-promise! from promesa.core (still available in promesa.impl).
Remove set-default-promise! helper (the user can do the same without the helper).
Remove attempt function (not useful).
Remove branch function (not useful).

New features and not breaking changes and fixes:

Add create promise constructor, a facility for create a promise using a factory function (before this is done passing a function to promise).
Add deferred promise constructor. The main purpose of this constructor is creating an empty promise ready to be resolved or rejected externally (using resolve! and reject!).
Add handle chain function: is some kind of combination of then' and catch. It chains a function to be executed when the promise is either normally or rejected (with first argument with resolved value (or nil) and second argument with the exception (or nil) if promise is rejected). Returns the promise resolved with the return value of the chained function. Does not flatten the result.
Add then' chain function. Is a variant of then function that does not flatten the result (a more performant variant).
Add chain' chain function helper. Is a chain variant that does not flatten the result (a more performant variant).
Rename alet to let (alet is stil awailable as alias for backward compatibility).
Add plet as syntactic abstraction/sugar for all composition operator.
Add race composition operator.
Add run! function (a promise aware run! variant).
Add promesa.exec namespace with Executors & Schedulers abstractions.
Add future macro (analogous to clojure.core/future that returns promise instance instead of Future, also works in cljs) that uses promesa.exec behind the schenes.
Improve let macro making it safe to synchronos exception that can be raised from the first evaluated expression. Now all exception raised inside let returs properly rejected promise.
Add loop/recur syntax abstraction.

Version 3.0.0

Date: 2019-08-21

This is a breaking change release; even though the majority of public (not experimental) api is not affected. Relevant changes are:

Remove promesa.async and promesa.async-cljs namespaces. They was experimental and finally they don't demonstrate to be useful in comparison to the complexity that they introduce.

Other changes:

Allow use promise on GraalVM native compilation.
Make promesa compatible with thenable objects (see issue #66).
Simplified alet macro implementation; it's no longer needs await for wait promise binding resolution.

Version 2.0.1

Date: 2019-03-30

Yo now can create an empty promise (without a factory function) and resolve or reject it using the new functions: resolve! reject!.

Example:

(require '[promesa.core :as p])

(let [pr (p/promise)]
  ;; do something
  (p/resolve! pr 2))

Version 2.0.0

Date: 2019-02-19

This is a breaking change release. Finally bluebird is gone in favour of using the ES6 builtin Promise object. This removes the overhead (in size) of the additional external library.

The reason of using bluebird initially was because native promises performed badly, but in new versions javascript engines the performance and memory usage is improved significantly. In any case you can still use the bluebird if you want, thanks to the new functions:

set-default-promise!: enables the user setting up a custom promise constructor as default one for promesa library.
extend-promise!: enables the user to use a custom promise implementation with promesa library abstractions.

Other (also probably breaking) changes:

timeout is now implemented in terms of internal scheduler facilities (bluebird impl was used previously) and it is now available for clojure (jvm).
any is reimplemented in clj/cljs and now accepts an additional argument for setting the default return value if promise is resolved. If default value is not provided, an ExceptionInfo will be throwed.

Version 1.9.0

Date: 2018-08-03

Update bluebird bundle to 3.5.0
Update dependencies.
Fix some issues on async macro (jvm only).
Fix issue with interop on alet macros.

Version 1.8.1

Date: 2017-04-20

Remove _ character from internal assets directory. That fixes incompatibilities with cordova/android build tools.

Version 1.8.0

Date: 2017-02-21

Update bluebird to 3.4.7
Fix wrong impl of sync introspection (on cljs).
Fix wrong impl of delay function (on cljs).
Fix behavior difference of then function on clj in respect to cljs.
Avoid compiler warnings caused by .finally/.catch
Add safer await detection on async macro (on cljs).

Version 1.7.0

Date: 2016-12-18

Fix clojure finally implementation.
Minor internal refactor. Public api should be fully backward compatible.

Version 1.6.0

Date: 2016-11-02

Add async macro that uses core.async machinary in order to build go like macro and allow to have fully async/await syntax.
Update bluebird to 3.4.6 (cljs underlying promise impl library).
Add support experimental support for native promises and other thenables.
Remove usage of clj->js and js->clj functions.

Version 1.5.0

Date: 2016-08-18

Make promise aware of clojure dynamic binding context (clj only).

Version 1.4.0

Date: 2016-07-10

Update bluebird to 3.4.1
Add missing Promise alias on externs (that fixes unexpected exceptions on advanced compilation modes).

Version 1.3.1

Date: 2016-06-08

Remove reflection warnings.

Version 1.3.0

Date: 2016-06-08

Update bluebird to 3.4.0
Improve internal impl (now splitted in few namespaces).
Fix bug in finally combinator function.
Add do* promise constructor (analogous to Promise.attempt).
Remove promise.monad namespace.

Version 1.2.0

Date: 2016-05-20

Add more bluebird externs.
Docstrings improvements.
Update bluebird to 3.3.5

Version 1.1.1

Date: 2016-03-19

Fix wrong call on IPrintWriter impl.
Add noConflict to externs.
Update cljs compiler to 1.8.34.

Version 1.1.0

Date: 2016-03-18

Add err and error alias as catch analougous function that has the parameters inverted in the same way as map and mapcat.

Version 1.0.0

Date: 2016-03-17

Add scheduler abstraction.
Add map function.
Add mapcat function.
Update bluebird to 3.3.4.
Remove wrapping logic from -bind impl.

Version 0.8.1

Date: 2016-02-13

Remove cats imports from core ns that causes import exception.

Version 0.8.0

Date: 2016-02-13

BREAKING CHANGE: Cats is no longer requred dependency. If you want use it you need import the promesa.monad ns.
Update bluebird to 3.3.0 (cljs).
Add bultin support for async/await like syntax.

Version 0.7.0

Date: 2016-01-08

Update bluebird to 3.1.1 (cljs).
Add better externs (with type annotations) (cljs).
Update cats dependency to 1.2.1.

Version 0.6.0

Date: 2015-12-03

Important changes:

Add clojure support (only with JDK8). Tha implies major code refactor. The public api should be mostly backwad compatible but it is possible regressions.

Other changes:

Update the cljs compiler version to 1.7.189
Update cats library to 1.2.0

Version 0.5.1

Date: 2015-09-27

Add 'branch' combinator

Version 0.5.0

Date: 2015-09-18

Update cats to 1.0.0
Adapt code to cats 1.0.0 breaking changes.
Add more tests.
Remove spread operator beacuse it is no longer needed (you can use clojure destructuring with then combinator.
Start using the -name protocol naming convention.
Update bluebird to 2.10.0