I haven’t used clojure in quite a while but what’s the issue with (let [a b] …)?

Is (let (a b) …) even valid clojure?

I believe it would be (let ‘(a b)), but I’m not sure if that’s valid or not. That’s how Racket does its version of defn

In CL and Scheme, it's (let ((var1 val) (var2 val)) body...). So parentheses are used for grouping and function/macro application. In Clojure, parens are just used for application, so you have e.g. (let [var1 val var2 val] body...), or (defn foo [x] ..) or (cond testa 1 testb 2 ...).

It takes some getting used to, and I do wish Clojure would do something more like (let [[var1 val] [var2 val]] ... .. though of course then you'd have to figure something else out for destructuring.

> `(let [a b] ...)` instead of `(let (a b) ...)` is _not_ okay

it is however quite consistent, clojure uses vector form for most macros that require a "control" form before a "data" form: argument list in defn, names list in let, iteration descriptors in for, etc. you get used to consistency quite easily.

> Eh? That's completely lifted from CL.

Clojure’s abstraction is a bit more far-reaching than Common Lisp’s SEQUENCE, implemented as interfaces rather than types.

A Clojure sequence is anything “seqable” (either implements the Seqable interface, or special case handling for host platform collections), not just lists and vectors. Hash maps, sets, Java Iterables, etc. are all seqable and work with the same standard collection functions.

e.g. you can `(map (fn [[k v]] …) {:a 1 :b 2})`, rather than needing a separate MAPHASH function.