> (def my-hash {:a 1 :b 2})

I don't know! That looks very unlispy. So much new syntax and inconsistent with the otherwise very uniform Lisp syntax.

The Racket alternative

> (define my-hash (make-hash)) > (hash-set! my-hash 'a 1) > (hash-set! my-hash 'b 2)

looks much much better to me!