Block sugar in expressions

from blog baby steps, | ↗ original
UPDATE: I found some more complications. Updates inline. I have been working on and off on allowing block sugar to appear in Rust expressions and not only statements. For those who do not know what I am talking about, let me give a bit of context. At the moment, one can write the following in Rust: vec::iter(v) { |e| ... } which is sugar...