Comment by derefr

No, you're right—arguments are always evaluated unless they're blocks in the full Smalltalk design we have today. However, like I said, this is a codified design pattern—the language could get away without doing it while still retaining the "core Smalltalk conceit" of everything being a message sent to an object. This is basically what the io language does—it's basically a Smalltalk at its core, but with less cruft.