There is too many "Void", omit it if no returned;

Thats an interesting idea, although I lean towards thinking that an explicit Void is on the side of "good verbosity". Plus I think it would make parsing harder and impact IDE tooling.

thanks! type inference also make parsing harder

another advice:

1. if return This,auto generation return this,because it's only allow to return this.
2. why shortcut a,b,c=>it.add(a).add(b).add(c) only for it-block.I want to use it like this list,1,2,4=>list.add(1).add(3).add(4)

f return This,auto generation return this,because it's only allow to return this.

It doesn't necessarily return this, it just returns something typed as this. I think this is a case where explicit and more verbose is probably a bit better then creating special rules

why shortcut a,b,c=>it.add(a).add(b).add(c) only for it-block.I want to use it like this list,1,2,4=>list.add(1).add(3).add(4)

The idea is that those adds should be wrapped in curly braces. For example this works just fine:

fansh> list := [,]
[,]
fansh> list { 1, 2, 3 }
[1, 2, 3]
fansh> 

Sorry,I falsely assumed that , is only shortcut for add().it's difficult to understand

I always wondered if maybe "Same" (or something else) would have been a better name than "This", which is so similar to "this" - a programming construct we intuitively associate with the current instance rather than the current class.