Hold onto your hat 🎩 here comes another zany syntax 💡 idea: So . has a meaning in vectors/sequences, but AFAIK isn't meaningful in maps. What would it mean in a map? Now in JavaScript es6 introduced the whole nifty object constructor shorthand thing: {a} means {:a 1} where a is bound to 1. This is actually pretty nice when you use long names: {very-descriptive-name} instead of {:very-descriptive-name very-descriptive-name} ES6 also allows you do do things like {foo: 1, ...m} which is kinda the same thing as Meander: (subst {:foo 1, & ?m}) But what Meander is missing is the nifty symbol => key value pair trick. So that's one thing you could use . for in a map! (subst {. very-descriptive-name}) => {:very-descriptive-name very-descriptive-name} Well, it's a little bit more complicated than that because you need to decide exactly what kind of things can be treated like this... should it be limited to memory variables? Any bound symbol? Not sure, but it is an interesting substitution use case. Pros: being able to provide a key/value pair in a single symbol is very popular in JavaScript. If substitution were allowed for this operator on non memory variables it might make for a very concise collection constructor. Cons: For rewrite patterns, we usually match on a single character name anyway, so it's likely only useful in the substitution phase, not with matches. Alternatives: % might be a better operator than . because it kinda looks like a key value thingy with the dot slash dot.