This isn’t really a thing, though: Common Lisp has built-in literal syntax for n-dimensional arrays and structs and libraries like fset provide literal syntax for Clojure-style immutable data structures.
I've used fset and cl21. The problem is that once you start using those you no longer are able to use libraries. Data structures have to be built into core.
The common lisp community has rejected reader macros for interop reasons the last time I checked (in the case of cl21)
Even the docs for fset doesn't show the use of data literals. it does things like (set) and (isetq s2 (set 'c 1 "foo" 'a 'c))
This pretty much proves my point. it's not fun typing (set 'c 1 "foo" 'a 'c) instead of #{'c 1 "foo" 'a 'c}. It's also not possible to put those on the wire (easily) for communication between common lisp processes. Breaking the whole point of homoiconicity.
> once you start using those you no longer are able to use libraries
This isn't true: if the libraries you use are designed to use generic functions for their internals, rather than normal functions. I've written code using custom data structures heavily, with little or no impact on which libraries I could use.
> The common lisp community has rejected reader macros
cl21 is just confusing matters here. Plenty of code uses named-readtables to use arbitrary reader macros.
I don't understand the "interop reasons" you're talking about: as long as you use named-readtables, interop basically Just Works.
> It's also not possible to put those on the wire (easily) for communication between common lisp processes. Breaking the whole point of homoiconicity.
It looks like you're right for the most part. Literals are supported if you use https://github.com/vseloved/rutils. If your cl-edn actually works then a combo of rutils and cl-edn could bring most of the value I found in clojure to common lisp.
Immutability by default is mostly overrated: I’ve written code in many languages (Haskell, Clojure, JS, CL, etc.), and I’ve found I care more whether a library (Immer, ramda, etc.) provides referentially transparent APIs than whether or not the language’s data-structures provide immutability guarantees.
But, additionally, my point was that CL has literal representations for arbitrary data types, not that you can get immutable datastructures from a library.
