[pcwalton]

> Second, this post demonstrates a danger of allowing assignment via '=' evaluate to an expression (granted with less weird precedence rules it wouldn't turn out as bad in this case).

I think it's just an issue of precedence. Assignment evaluates to an expression in all Lisps, ML, Haskell, Scala, and Rust, without this issue.

Stricter typing can also solve the problem. If assignment evaluates to unit, as it does in ML/Haskell/Scala/Rust to name a few, then the attempt to perform the logical-and operation with unit and bool would throw (in a dynamically typed language) or won't compile (in a statically typed language).