weekly 2023-12-25
MoonBit Updateβ
01. Added built-in type Result
β
enum Result[T, E] {
Ok(T)
Err(E)
}
02. Added the question mark operatorβ
A new question mark operator has been introduced to simplify error handling:
fn may_fail() -> Option[Int] { ... }
fn compose_may_fail() -> Option[String] {
let x = may_fail()?
let y = may_fail()?.lsr(3)
Some ((x + y).to_string())
}
The semantics of the question mark operator are: if t
in t?
results in None
, then t?
is equivalent to return None
(exiting the current function). If t?
results in Some(x)
, then t?
is equivalent to x
. Besides Option
type, the question mark operator can also be used with Result
type:
fn may_error() -> Result[Int, String] { ... }
fn compose_may_error() -> Result[Int, String] {
let x = may_error()?
let y = may_error()?
if y == 0 {
return Err("divide by zero")
}
Ok (x / y)
}
03. The keyword interface
has been changed to trait
β
Based on community feedback, the keyword interface
has been changed to trait
, and the interface
keyword is temporarily retained.
04. Modified the logic for dead code eliminationβ
Top-level let
statements not used are always considered removable, regardless of side effects. For example,
let a = 1 // will be removed
let b: T = f(a) // will be removed
fn init {
.. // a and b are not used
}
If the function f
has side-effects, move it to fn init { .. }
to prevent it from being removed.
05. Fixed issues where the code formatting tool did not correctly handle Chinese comments.β
06. Fixed issues with handling Chinese global identifiers.β
IDE Updateβ
01. Added an option to control whether moon check
starts automatically.β
VSCode users can use moonbit.autoMoonCheck.enable
in settings.json
to control whether moon check
starts automatically. Or, you can search "moonbit:" in the settings.
02. Fixed a bug where derive(Show)
incorrectly reported errors.β
Before the fix:
After the fix:
Build System Updateβ
01. Added the moon doc
command for generating and previewing documentation.β
moon doc --serve
will create documentation based on markdown comments in the code and launch a web server locally. Accessing the provided link allows you to view the results.