feat(trampoline): add a trampoline module (@endo/trampoline) #2263

boneskull · 2024-05-01T23:07:58Z

we will probably need something like this. based on work by @naugtur

UPDATE: I plan to use this in #2310 and someone should eventually refactor ses to use it.

mhofman · 2024-05-02T00:42:42Z

packages/trampoline/README.md

+
+From [Wikipedia](https://en.wikipedia.org/wiki/Trampoline_(computing)):
+
+> A trampoline is a loop that iteratively invokes [thunk](https://en.wikipedia.org/wiki/Thunk_(functional_programming))-returning functions ([continuation-passing style](https://en.wikipedia.org/wiki/Continuation-passing_style)).


I would like to highlight that this is one of the usage of the word "trampoline" in programming contexts, and I've actually used trampoline to refer to other usages (in particular a piece of code that allows me to reach another context).

I'd prefer if we named this package in a way that reflects the generator iteration model that this trampoline uses.

To be clear, you're not saying, "don't call it a trampoline", yes? There is precedent in the JS ecosystem for this meaning.

I would prefer we name it something silly, of course.

Open to suggestions. I like rainbow-trampoline, because it supports functions of any color 🌈.

Function coloring is also a loaded term. Sync/async coloring is currently the main kind in JS, but coloring has been used in the context of a couple other proposals lately.

I can, without rancor, use the more-widely-understood meaning of words within their context (in this case, the community of JavaScript developers) while disregarding those less-widely-understood meanings. Naming is hard and we do the best we can 😄

But if you (or anyone else) has a suggestion for naming this package, please offer it!

optional-a-sync

@mhofman @boneskull need more razors for this yak shaving?

I tend to use GPT for seeding name ideas. gpt-4o is really bad at it tho, had to go back to gpt-4
Here are some not awful seeds which we could use as inspiration for coming up with something reasonable.

1. AsyncBridge 2. SyncAsyncHarmonizer 3. JumpSync 4. YieldBounce 5. GenTrampolinator 6. AsyncOrNot 8. CodeChameleon 12. SyncAsyncLeap 16. AsyncFlip 17. YieldFlex 18. BounceBetween 19. SyncAsyncFusion

I still stand by optional-a-sync but these could also work from above:
async-or-not sync-async-chameleon sync-async-bridge

Also, I honestly don't see anything wrong in using the word trampoline in an opinionated way. All packages called trampoline that I've found are using it in various meanings unrelated to each other.

I would like to name this trampoline.

I'd name it "The Right Honourable Boris von Mejía" if it were totally up to me, but I can live with @endo/trampoline.

boneskull · 2024-08-01T23:43:17Z

packages/trampoline/package.json

+  "private": true,
+  "eslintConfig": {
+    "extends": [
+      "plugin:@endo/internal"


I copy/pasted this.

I don't understand why this is here and why we are pulling in all of those eslint dev deps.

Also, I am not sure why we're pulling in all of these dev deps in any workspace.

Why not let them all live in the monorepo root?

Let’s follow-up about this separately and solve it homogeneously if we can. The config for ses and below is a little different than above ses, where we can count on Hardened JavaScript for some invariants. But, otherwise, if we can hoist more, I’m in favor.

If we are going to use this package in SES, it requires the more-strict lint (no-polymorphic-call), and I assume you’re shooting for that. (to follow-up with a SES refactor). There’ll be a bit of duplication with uncurryThis and getting commons.

@naugtur did you review this with a close eye on whether this would interfere with Hermes?

packages/trampoline/src/trampoline.js

naugtur · 2024-08-27T07:53:54Z

packages/trampoline/README.md

+
+## What is this?
+
+The pattern exposed by this library—known as [trampolining][]—helps manage control flow in a way that avoids deep recursion and potential stack overflows. It effectively "converts" recursive calls into a loop. This is especially helpful in a language like JavaScript [because reasons][proper-tail-calls].


This line remains slightly confusing - first time reading it I didn't grok that it's describing what the library is NOT.

Suggested change

The pattern exposed by this library—known as [trampolining][]—helps manage control flow in a way that avoids deep recursion and potential stack overflows. It effectively "converts" recursive calls into a loop. This is especially helpful in a language like JavaScript [because reasons][proper-tail-calls].

This library is not just an implementation of [trampolining][] that helps manage control flow in a way that avoids deep recursion and potential stack overflows (by turning recursive calls into a loop).

I don't think [proper-tail-calls] is something we want to discuss here as the goal of this trampoline is not that. It's to allow deduplicating logic when both sync and async implementations are needed.

for posterity: even if it is not an explicit goal, we get mitigation of the lack of proper TCO for free. right?

packages/trampoline/README.md

packages/trampoline/src/types.ts

kriskowal

I like it. I agree with @naugtur that it should export syncTrampoline and asyncTrampoline without leaving the consumer to guess which of these trampoline aliases.

packages/trampoline/README.md

kriskowal · 2024-09-06T22:39:21Z

packages/trampoline/package.json

+  "private": true,
+  "eslintConfig": {
+    "extends": [
+      "plugin:@endo/internal"


Let’s follow-up about this separately and solve it homogeneously if we can. The config for ses and below is a little different than above ses, where we can count on Hardened JavaScript for some invariants. But, otherwise, if we can hoist more, I’m in favor.

If we are going to use this package in SES, it requires the more-strict lint (no-polymorphic-call), and I assume you’re shooting for that. (to follow-up with a SES refactor). There’ll be a bit of duplication with uncurryThis and getting commons.

@naugtur did you review this with a close eye on whether this would interfere with Hermes?

kriskowal · 2024-09-06T22:40:22Z

packages/trampoline/src/trampoline.js

+ */
+const { getPrototypeOf } = Object;
+const { bind } = Function.prototype;
+const uncurryThis = bind.bind(bind.call); // eslint-disable-line @endo/no-polymorphic-call


Mind that the rule might not be enabled for this package (and probably should be enabled)

the eslint rule that warns if eslint directives are unused should be enabled 😄

boneskull · 2024-09-09T22:37:13Z

The only thing I dislike about this now is the trampoline export - syncTrampoline and asyncTrampoline are a perfect pair. There's not much special about the async one and using only one of them doesn't make much sense.

trampoline has been removed; now only asyncTrampoline and syncTrampoline exist

This package will be used by `@endo/compartment-mapper` and potentially `ses`.

boneskull self-assigned this May 1, 2024

boneskull added the enhancement New feature or request label May 1, 2024

mhofman reviewed May 2, 2024

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boneskull force-pushed the boneskull/supertramp branch 2 times, most recently from f419a5d to 894f91a Compare August 1, 2024 23:30

boneskull marked this pull request as ready for review August 1, 2024 23:30

boneskull changed the title ~~feat(trampoline): [DRAFT] add a trampoline module~~ feat(trampoline): add a trampoline module Aug 1, 2024

boneskull changed the title ~~feat(trampoline): add a trampoline module~~ feat(trampoline): add a trampoline module (@endo/trampoline) Aug 1, 2024

boneskull requested review from kriskowal and naugtur August 1, 2024 23:36

boneskull commented Aug 1, 2024

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boneskull force-pushed the boneskull/supertramp branch from 894f91a to 41c0d0c Compare August 15, 2024 22:43

boneskull mentioned this pull request Aug 15, 2024

support dynamic requires #2310

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naugtur reviewed Aug 26, 2024

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kriskowal approved these changes Sep 6, 2024

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boneskull force-pushed the boneskull/supertramp branch from f8eceed to b40b431 Compare September 9, 2024 22:35

feat(trampoline): create @endo/trampoline

9e8b86d

This package will be used by `@endo/compartment-mapper` and potentially `ses`.

boneskull force-pushed the boneskull/supertramp branch from b40b431 to 9e8b86d Compare September 10, 2024 20:55

boneskull merged commit 4406f5d into master Sep 10, 2024
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boneskull deleted the boneskull/supertramp branch September 10, 2024 21:13

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feat(trampoline): add a trampoline module (@endo/trampoline) #2263

feat(trampoline): add a trampoline module (@endo/trampoline) #2263

boneskull commented May 1, 2024 •

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boneskull commented Sep 9, 2024


		From [Wikipedia](https://en.wikipedia.org/wiki/Trampoline_(computing)):

		> A trampoline is a loop that iteratively invokes [thunk](https://en.wikipedia.org/wiki/Thunk_(functional_programming))-returning functions ([continuation-passing style](https://en.wikipedia.org/wiki/Continuation-passing_style)).


		## What is this?

		The pattern exposed by this library—known as [trampolining][]—helps manage control flow in a way that avoids deep recursion and potential stack overflows. It effectively "converts" recursive calls into a loop. This is especially helpful in a language like JavaScript [because reasons][proper-tail-calls].

	The pattern exposed by this library—known as [trampolining][]—helps manage control flow in a way that avoids deep recursion and potential stack overflows. It effectively "converts" recursive calls into a loop. This is especially helpful in a language like JavaScript [because reasons][proper-tail-calls].
	This library is not just an implementation of [trampolining][] that helps manage control flow in a way that avoids deep recursion and potential stack overflows (by turning recursive calls into a loop).

feat(trampoline): add a trampoline module (@endo/trampoline) #2263

feat(trampoline): add a trampoline module (@endo/trampoline) #2263

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