Change from infix bang to infix wavy-dot

[erights]

Infix bang and infix bang-dot both conflict with TypeScript. Whatever syntax we do propose, we'd like it to be adopted by TypeScript as well. Infix wavy-dot, ~. is currently the leading candidate. Presumably, it would combine with optional chaining either by ?~. or ~?..

[warner]

What would "optional chaining" do? I'm imagining something that short-circuits, so in p = x~.foo()~?.bar()~?.baz(), if foo() resolves to undefined then p is resolved to undefined and bar/baz are not invoked.