feat(tazjin/generator-example): add an example for genawaiter crate
This is an experiment for tvix-eval. Change-Id: Ic752b5b125cefefeb1343e38a70beb364478e6eb Reviewed-on: https://cl.tvl.fyi/c/depot/+/8131 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
This commit is contained in:
Vincent Ambo
tazjin
parent
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commit
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5 changed files with 260 additions and 0 deletions
1
users/tazjin/generator-example/.gitignore
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users/tazjin/generator-example/.gitignore
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/target
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124
users/tazjin/generator-example/Cargo.lock
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users/tazjin/generator-example/Cargo.lock
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# This file is automatically @generated by Cargo.
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# It is not intended for manual editing.
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version = 3
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[[package]]
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name = "genawaiter"
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version = "0.99.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "c86bd0361bcbde39b13475e6e36cb24c329964aa2611be285289d1e4b751c1a0"
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dependencies = [
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"genawaiter-macro",
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"genawaiter-proc-macro",
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"proc-macro-hack",
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]
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[[package]]
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name = "genawaiter-macro"
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version = "0.99.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "0b32dfe1fdfc0bbde1f22a5da25355514b5e450c33a6af6770884c8750aedfbc"
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[[package]]
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name = "genawaiter-proc-macro"
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version = "0.99.1"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "784f84eebc366e15251c4a8c3acee82a6a6f427949776ecb88377362a9621738"
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dependencies = [
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"proc-macro-error",
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"proc-macro-hack",
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"proc-macro2",
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"quote",
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"syn",
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]
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[[package]]
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name = "generator-example"
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version = "0.1.0"
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dependencies = [
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"genawaiter",
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]
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[[package]]
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name = "proc-macro-error"
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version = "0.4.12"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "18f33027081eba0a6d8aba6d1b1c3a3be58cbb12106341c2d5759fcd9b5277e7"
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dependencies = [
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"proc-macro-error-attr",
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"proc-macro2",
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"quote",
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"syn",
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"version_check",
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]
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[[package]]
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name = "proc-macro-error-attr"
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version = "0.4.12"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "8a5b4b77fdb63c1eca72173d68d24501c54ab1269409f6b672c85deb18af69de"
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dependencies = [
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"proc-macro2",
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"quote",
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"syn",
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"syn-mid",
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"version_check",
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]
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[[package]]
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name = "proc-macro-hack"
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version = "0.5.20+deprecated"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "dc375e1527247fe1a97d8b7156678dfe7c1af2fc075c9a4db3690ecd2a148068"
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[[package]]
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name = "proc-macro2"
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version = "1.0.51"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "5d727cae5b39d21da60fa540906919ad737832fe0b1c165da3a34d6548c849d6"
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dependencies = [
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"unicode-ident",
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]
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[[package]]
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name = "quote"
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version = "1.0.23"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "8856d8364d252a14d474036ea1358d63c9e6965c8e5c1885c18f73d70bff9c7b"
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dependencies = [
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"proc-macro2",
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]
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[[package]]
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name = "syn"
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version = "1.0.107"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "1f4064b5b16e03ae50984a5a8ed5d4f8803e6bc1fd170a3cda91a1be4b18e3f5"
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dependencies = [
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"proc-macro2",
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"quote",
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"unicode-ident",
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]
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[[package]]
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name = "syn-mid"
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version = "0.5.3"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "baa8e7560a164edb1621a55d18a0c59abf49d360f47aa7b821061dd7eea7fac9"
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dependencies = [
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"proc-macro2",
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"quote",
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"syn",
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]
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[[package]]
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name = "unicode-ident"
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version = "1.0.6"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "84a22b9f218b40614adcb3f4ff08b703773ad44fa9423e4e0d346d5db86e4ebc"
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[[package]]
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name = "version_check"
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version = "0.9.4"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
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9
users/tazjin/generator-example/Cargo.toml
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9
users/tazjin/generator-example/Cargo.toml
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[package]
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name = "generator-example"
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version = "0.1.0"
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edition = "2021"
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# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
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[dependencies]
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genawaiter = "0.99.1"
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11
users/tazjin/generator-example/README.md
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users/tazjin/generator-example/README.md
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generator-example
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=================
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This is an experiment with the [`genawaiter`][] crate, to see if it
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could be suitable for dealing with the execution flattening problem in
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Tvix.
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It constructs a dummy example that is similar to some of the problems
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we have in Tvix that require generator-like thunk forcing.
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[`genawaiter`]: https://docs.rs/genawaiter/latest/genawaiter/index.html
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115
users/tazjin/generator-example/src/main.rs
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115
users/tazjin/generator-example/src/main.rs
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use genawaiter::rc::{Co, Gen};
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use std::cell::RefCell;
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use std::future::Future;
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use std::pin::Pin;
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use std::rc::Rc;
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#[derive(Debug)]
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enum ValueRepr {
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Int(i64),
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Thunk((i64, i64)),
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}
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#[derive(Clone, Debug)]
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struct Value(Rc<RefCell<ValueRepr>>);
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impl Value {
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fn force(&self) {
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let mut inner = self.0.borrow_mut();
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match *inner {
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ValueRepr::Int(_) => return,
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ValueRepr::Thunk((a, b)) => {
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*inner = ValueRepr::Int(a + b);
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}
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}
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}
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fn is_forced(&self) -> bool {
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matches!(*self.0.borrow(), ValueRepr::Int(_))
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}
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fn int(&self) -> i64 {
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match *self.0.borrow() {
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ValueRepr::Int(i) => i,
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ValueRepr::Thunk(_) => panic!("unforced thunk!"),
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}
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}
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}
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impl From<i64> for Value {
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fn from(value: i64) -> Self {
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Value(Rc::new(RefCell::new(ValueRepr::Int(value))))
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}
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}
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impl From<(i64, i64)> for Value {
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fn from(value: (i64, i64)) -> Self {
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Value(Rc::new(RefCell::new(ValueRepr::Thunk(value))))
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}
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}
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async fn list_maker(values: Vec<Value>, co: Co<Value>) -> Vec<i64> {
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let mut output: Vec<i64> = vec![];
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for value in values {
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if !value.is_forced() {
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co.yield_(value.clone()).await;
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}
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output.push(value.int());
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}
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output
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}
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async fn list_reverser(values: Vec<Value>, co: Co<Value>) -> Vec<i64> {
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let mut output = list_maker(values, co).await;
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output.reverse();
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output
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}
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struct Frame {
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gen: Gen<Value, (), Pin<Box<dyn Future<Output = Vec<i64>>>>>,
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}
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fn pin_future(
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f: impl Future<Output = Vec<i64>> + 'static,
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) -> Pin<Box<dyn Future<Output = Vec<i64>>>> {
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Box::pin(f)
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}
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fn main() {
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let mut frames: Vec<Frame> = vec![];
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let values: Vec<Value> = vec![
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42.into(),
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(12, 54).into(),
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4.into(),
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(40, 2).into(),
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2.into(),
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];
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let second = values.clone();
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frames.push(Frame {
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gen: Gen::new(|co| pin_future(list_maker(values, co))),
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});
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frames.push(Frame {
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gen: Gen::new(|co| pin_future(list_reverser(second, co))),
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});
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for (idx, mut frame) in frames.into_iter().enumerate() {
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loop {
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match frame.gen.resume() {
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genawaiter::GeneratorState::Yielded(val) => {
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println!("yielded {:?} in frame {}", val, idx);
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val.force();
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}
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genawaiter::GeneratorState::Complete(list) => {
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println!("result {}: {:?}", idx, list);
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break;
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}
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}
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}
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}
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}
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