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followup #16871 asyncjs.then: allow pipelining procs returning futures#17189

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timotheecour:pr_16871_followup_asyncjs_then
Mar 4, 2021
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followup #16871 asyncjs.then: allow pipelining procs returning futures#17189
Araq merged 15 commits intonim-lang:develfrom
timotheecour:pr_16871_followup_asyncjs_then

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@timotheecour timotheecour commented Feb 25, 2021 •
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followup #16871

  • then now allows pipelining futures (instead of just callbacks), and we avoid returning Future[Future[T]] which would be wrong (would break the monadic property that allows pipelining
  • increase test coverage, eg then with onReject callback is now tested
  • factored the 3 then overloads into a single proc, which is cleaner for docs etc (in fact it would've been 6 overloads with the added support for futures, until i figured out how to use a single non-overloaded proc)
  • introduces typeOrVoid (which I'll expose in typetraits in future work)

future work

  • expose typeOrVoid or make typeof(someProcReturningVoid()) is void work
  • remove nimExperimentalAsyncjsThen flag once stabilized

@timotheecour timotheecour mentioned this pull request Feb 26, 2021
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@timotheecour timotheecour marked this pull request as ready for review February 26, 2021 04:40
ringabout
ringabout reviewed Feb 26, 2021
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@timotheecour timotheecour force-pushed the pr_16871_followup_asyncjs_then branch from 12ac0fe to 006b55b Compare February 26, 2021 07:54
@timotheecour timotheecour mentioned this pull request Feb 26, 2021
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@timotheecour timotheecour requested a review from Araq February 27, 2021 20:02
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timotheecour commented Feb 27, 2021 •
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ping @Araq after this PR, fetch (from #12531) works [1]

# funs.nim
from std/jsffi import JsObject
import std/[jsfetch,asyncjs,sugar,jsconsole]
proc main {.async.} =
  await fetch("https://api.github.com/users/manishmshiva".cstring)
    .then((response: Response) => response.json())
    .then((json: JsObject) => console.log(json))
    .catch((err: Error) => console.log("Request Failed", err))

  await fetch("https://D20210227T115923_bad_url".cstring)
    .then((response: Response) => response.json())
    .then((json: JsObject) => console.log(json))
    .catch((err: Error) => console.log("Request Failed from nim", err))
discard main()

which allows easy port from js code like this https://www.freecodecamp.org/news/javascript-fetch-api-tutorial-with-js-fetch-post-and-header-examples/

// GET Request.
fetch('https://api.github.com/users/manishmshiva')
    // Handle success
    .then(response => response.json())  // convert to json
    .then(json => console.log(json))    //print data to console
    .catch(err => console.log('Request Failed', err)); // Catch errors

in a broswer, the following html:

<!DOCTYPE html>
<html>
<script src="funs.js"></script>
<body>
</body>
</html>

shows:
image

[1] I had to modify #12531 as follows /cc @juancarlospaco

diff --git a/lib/std/jsfetch.nim b/lib/std/jsfetch.nim
index 93ae44261..cf310174b 100644
--- a/lib/std/jsfetch.nim
+++ b/lib/std/jsfetch.nim
@@ -72,7 +72,7 @@ func clone*(self: Response or Request): Response {.importjs: "#.$1()".}
 proc text*(self: Body or Request): Future[cstring] {.importjs: "#.$1()".}
   ## https://developer.mozilla.org/en-US/docs/Web/API/Body/text

-proc json*(self: Body): Future[JsObject] {.importjs: "#.$1()".}
+proc json*(self: Response): Future[JsObject] {.importjs: "#.$1()".}
   ## https://developer.mozilla.org/en-US/docs/Web/API/Body/json

 proc formData*(self: Body): Future[FormData] {.importjs: "#.$1()".}

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juancarlospaco commented Feb 27, 2021

It is a relevant change, therefore needs another line on the changelog. IMHO.

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timotheecour commented Feb 27, 2021 •
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I think it's already covered by the existing one:

- Added `then`, `catch` to `asyncjs`, for now hidden behind `-d:nimExperimentalAsyncjsThen`.

@timotheecour timotheecour added the TODO: followup needed remove tag once fixed or tracked elsewhere label Feb 27, 2021
@timotheecour timotheecour mentioned this pull request Mar 3, 2021
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@timotheecour timotheecour force-pushed the pr_16871_followup_asyncjs_then branch from 6eb67e1 to bb26bd1 Compare March 4, 2021 09:16
@timotheecour timotheecour mentioned this pull request Mar 4, 2021
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@timotheecour timotheecour requested a review from dom96 March 4, 2021 10:15
@Araq Araq merged commit a66637b into nim-lang:devel Mar 4, 2021
@timotheecour timotheecour deleted the pr_16871_followup_asyncjs_then branch March 4, 2021 15:28
ringabout pushed a commit to ringabout/Nim that referenced this pull request Mar 22, 2021
@timotheecour @ringabout
followup nim-lang#16871 asyncjs.then: allow pipelining procs returnin…
d1683d5 
…g futures (nim-lang#17189)

* followup nim-lang#16871 asyncjs.then: allow pipelining procs returning futures
* rename test files where they belong
* fix tests
* tests for then with `onReject` callback
* rename test file containing fail to avoid messing with grep
* address comments
* cleanup
* un-disable 1 test
ardek66 pushed a commit to ardek66/Nim that referenced this pull request Mar 26, 2021
@timotheecour @ardek66
followup nim-lang#16871 asyncjs.then: allow pipelining procs returnin…
3444a3e 
…g futures (nim-lang#17189)

* followup nim-lang#16871 asyncjs.then: allow pipelining procs returning futures
* rename test files where they belong
* fix tests
* tests for then with `onReject` callback
* rename test file containing fail to avoid messing with grep
* address comments
* cleanup
* un-disable 1 test
@metagn metagn removed the TODO: followup needed remove tag once fixed or tracked elsewhere label Jan 4, 2024
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@ringabout ringabout ringabout approved these changes

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@timotheecour @juancarlospaco @ringabout @Araq @metagn