feat: update list functions to handle error polymorphism #2353
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Documentation doesn't reflect error handling capabilitiesCategory /// Maps elements using f, which may raise errors
/// ```mbt
/// // Success case
/// assert_eq(@list.of([1, 2]).map(fn(x){ x * 2}), @list.of([2, 4]))
/// // Error case
/// @list.of([1]).map(fn(x) { raise "error" }) // raises error
/// ```
**Reasoning**
The current documentation only shows successful cases. Since error handling is now part of the API contract, users should understand when and how errors can occur.
</details>
<details>
<summary> Inconsistent error handling in fold operations </summary>
**Category**
Correctness
**Code Snippet**
pub fn[A, B] rev_fold(self : T[A], init~ : B, (B, A) -> B) -> B
pub fn[A, B] fold(self : T[A], init~ : B, f : (B, A) -> B raise?) -> B raise?
**Recommendation**
Add raise? annotations to rev_fold for consistency:
```moonbit
pub fn[A, B] rev_fold(self : T[A], init~ : B, f : (B, A) -> B raise?) -> B raise?
**Reasoning**
fold and rev_fold are complementary operations but have different error handling capabilities. This inconsistency could lead to unexpected behavior when refactoring code.
</details>
<details>
<summary> Potentially redundant error propagation in nested operations </summary>
**Category**
Maintainability
**Code Snippet**
pub fn[A, B] scan_right(self : T[A], f : (B, A) -> B raise?, init~ : B) -> T[B] raise? {
self.rev().scan_left(f, init~).reverse_inplace()
}
**Recommendation**
Consider consolidating error handling for composite operations:
```moonbit
pub fn[A, B] scan_right(self : T[A], f : (B, A) -> B raise?, init~ : B) -> T[B] raise? {
try {
let reversed = self.rev()
let scanned = reversed.scan_left(f, init~)
scanned.reverse_inplace()
}
}
**Reasoning**
The current implementation chains operations that can raise errors. Making the error flow more explicit would help with debugging and make the code's intent clearer.
</details> |
Pull Request Test Coverage Report for Build 45Details
💛 - Coveralls |
peter-jerry-ye
approved these changes
Jun 26, 2025
9c2fa7a to
725d264
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