Do not force the declaration unused callback params

[gchumillas]

Describe the feature

Do not force programmers to declare unused callback parameters.

Use Case

Currently we are forced to declare all params, even though we are not going to use them. This adds unnecessary "noise" to the source code:

struct Event {}
struct Element {}

fn (target Element) on_click(callback fn (event Event)) {
	// ...
}

fn main() {
	el := Element{}

	el.on_click(fn(_ Event) {
		// performs some action
	})
}

Proposed approach:

struct Event {}
struct Element {}

fn (target Element) on_click(callback fn (event Event)) {
	// ...
}

fn main() {
	el := Element{}

	// omit the unused params, as we don't need them
	el.on_click(fn() {
		// performs some action
	})
}

Proposed Solution

The checker shouldn't complain about missing callback parameters.

Other Information

No response

Acknowledgements

• [ ] I may be able to implement this feature request
• [ ] This feature might incur a breaking change

Version used

V 0.4.10 3f76b69

Environment details (OS name and version, etc.)

V full version	V 0.4.10 dead5e69b44b4f8c4999ac82b730c21250cb0583.3f76b69
OS	macos, macOS, 15.4.1, 24E263
Processor	8 cpus, 64bit, little endian, Apple M1 Pro
Memory	0.16GB/16GB
V executable	/Users/gonzalo/Projects/Personal/v/nv/v
V last modified time	2025-05-10 22:09:09
V home dir	OK, value: /Users/gonzalo/Projects/Personal/v/nv
VMODULES	OK, value: /Users/gonzalo/.vmodules
VTMP	OK, value: /tmp/v_501
Current working dir	OK, value: /Users/gonzalo
Git version	git version 2.39.1
V git status	weekly.2025.19-14-g8ce8749f
.git/config present	true
cc version	Apple clang version 17.0.0 (clang-1700.0.13.3)
gcc version	Apple clang version 17.0.0 (clang-1700.0.13.3)
clang version	Apple clang version 17.0.0 (clang-1700.0.13.3)
tcc version	tcc version 0.9.28rc 2024-02-05 HEAD@105d70f7 (AArch64 Darwin)
tcc git status	thirdparty-macos-arm64 e447816c
emcc version	N/A
glibc version	N/A

[!NOTE] You can use the 👍 reaction to increase the issue's priority for developers.

Please note that only the 👍 reaction to the issue itself counts as a vote. Other reactions and those to comments will not be taken into account.

[huly-for-github[bot]]

Connected to Huly®: V_0.6-22830

[jorgeluismireles]

The feature could be extended for interfaces implementations where none of a given method arguments are used. Since v doesn't permit method overloading no two methods have the same name (different args) to cause any problem.

interface Reader {
    config(params string)
    read(data string)
}

struct FastReader implements Reader { }
fn (f FastReader) config() { ... } // I don't use params
fn (f FastReader) read(data string) { ... }