Use list

[bzy-debug]

closes #1

[Copilot]

Pull Request Overview

This PR refactors the StringZipper data structure to use @list.List instead of Array for the left and right collections, improving performance and simplifying the implementation. The change addresses issue #1 by leveraging the more appropriate list data structure for prepend/append operations.

• Replaced Array fields with @list.List for left and right string view collections
• Updated all array operations to use corresponding list operations (pattern matching, add, each)
• Modified CI workflow to use nightly MoonBit version

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
string_zipper.mbt	Converts Array fields to @list.List and updates all related operations to use list-specific methods
.github/workflows/ci.yml	Updates MoonBit installation to use nightly version

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[Copilot]

The add method prepends to the beginning of the list, but based on the context and comment about 'reverse order', this should use cons or prepend for clarity. If add appends to the end, the logic in to_string_and_pos and to_string_debug would be incorrect.

Suggested change

	list.add(view)
	list.prepend(view)

[coveralls]

Pull Request Test Coverage Report for Build 6

Details

• 44 of 45 (97.78%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.06%) to 95.294%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
string_zipper.mbt	44	45	97.78%

Totals
Change from base Build 3:	0.06%
Covered Lines:	162
Relevant Lines:	170

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💛 - Coveralls

[peter-jerry-ye-code-review]

Inefficient array conversion in string building operations

Category
Performance
Code Snippet
let left_array = self.left.to_array()
for i = left_array.length() - 1; i >= 0; i = i - 1 {
builder.write_string(left_array[i].to_string())
}
Recommendation
Use list iteration directly or implement a reverse iteration method for lists to avoid the overhead of converting to array
Reasoning
Converting a list to array just for reverse iteration creates unnecessary memory allocation and copying overhead, especially for large lists

Inconsistent absolute position calculation in drop_until_internal

Category
Correctness
Code Snippet
let abs_pos = from.abs_pos + from.current.length()
...
let abs_pos = from.abs_pos + rel_pos
Recommendation
Ensure consistent absolute position calculation logic across both branches, likely using the same formula or clearly documenting why they differ
Reasoning
The absolute position calculation differs between the two branches - one adds current.length() while the other adds rel_pos, which may lead to incorrect cursor positioning

Repeated pattern matching on list structure

Category
Maintainability
Code Snippet
match self.right {
Empty => ...
More(current, tail=new_right) => ...
}
Recommendation
Extract common list operations into helper functions like pop_front and is_empty to reduce code duplication and improve readability
Reasoning
The same pattern matching structure appears multiple times throughout the code, making it harder to maintain and potentially error-prone when the list structure changes