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[RFC[ Add bubble sort as an additional example.

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This was the inspiring example.
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Alessandro Coglio 2021-07-21 00:09:17 -07:00
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docs/rfc/005-countdown-loops.md
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@ -22,8 +22,8 @@ This proposal suggests adding countdown loops and inclusive loop ranges into the
# Motivation
In the current design of the language only incremental ranges are allowed. Though
in some cases there's a need for loops going in the reverse direction. This example
demonstrates the shaker sort algorithm where countdown loops are mocked:
in some cases there's a need for loops going in the reverse direction. These examples
demonstrate the shaker sort and bubble sort algorithms where countdown loops are mocked:
```ts
function shaker_sort(a: [u32; 10], const rounds: u32) -> [u32; 10] {
@ -49,7 +49,22 @@ function shaker_sort(a: [u32; 10], const rounds: u32) -> [u32; 10] {
}
```
Having a countdown loop in the example above could improve readability and
```ts
function bubble_sort(a: [u32; 10]) -> [u32; 10] {
for i in 0..9 { // i counts up
for j in 0..9-i { // i is flipped
if (a[j] > a[j+1]) {
let tmp = a[j];
a[j] = a[j+1];
a[j+1] = tmp;
}
}
}
return a
}
```
Having a countdown loop in the examples above could improve readability and
usability of the language by making it more natural to the developer.
However, if we imagined this example using a countdown loop, we would see that
@ -114,9 +129,9 @@ there are several cases to consider:
Cases 3 and 5 consist of one or more iterations; cases 4 and 6 consist of two or more iterations.
## Example
## Examples
The code example demostrated in the Motivation part of this document
The code examples demostrated in the Motivation part of this document
could be extended (or simplified) with the suggested syntax:
```ts
@ -142,6 +157,21 @@ function shaker_sort(a: [u32; 10], const rounds: u32) -> [u32; 10] {
}
```
```ts
function bubble_sort(a: [u32; 10]) -> [u32; 10] {
for i in 9..0 { // counts down
for j in 0..i { // no flipping
if (a[j] > a[j+1]) {
let tmp = a[j];
a[j] = a[j+1];
a[j+1] = tmp;
}
}
}
return a
}
```
# Drawbacks
No obvious drawback.