snoop VS ghostwheel

and if you want something closer to the guardrails syntax there is: https://github.com/CrypticButter/snoop

I've been using it together with https://github.com/CrypticButter/snoop it has been great and really hitting the sweet-spot of what you could expect from a type system.

You can take a look at malli instead of spec. Then take a look at the snoop library (https://github.com/CrypticButter/snoop) that provides some goodies on top of malli to easily define schema for function parameters and return types.

big fan of fulcro logic, but isn’t this almost identical to https://github.com/gnl/ghostwheel ?

if all you care about is information / documentation, and maybe validation, then spec or malli are fine. using spec during runtime to simulate a type system is a poor choice in most cases, because you are doing runtime type checking (something akin to dependent types or even esoteric contracts that are hard/impossible to express statically). There are some libs that help bolt a typed facade (using spec) onto the familiar defn / fn, https://github.com/gnl/ghostwheel https://github.com/Provisdom/defn-spec .