ghostwheel VS truss

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 .

When type checking is needed, I find the Truss library* does the trick quite well.

As for the syntax, there is very little, which can make it a harder lift but once you have the hang of it you won't deal with the issues identified in the parent comment.

* https://github.com/taoensso/truss

I use truss extensively throughout my code to prevent those types of errors.

I haven't tried it myself. I generally just use truss for runtime constraint checking. I use a modified version that integrates scope-capture. And malli validation for more complex cases, but I try to limit that. For me it is better to validate individual attributes as needed, vs validating an entire "type"/collection of attributes. So each function only cares about the attributes that it needs, and validates only as needed.

Use assertions for all data requirements inside functions - I use a modified version of https://github.com/ptaoussanis/truss to ensure that I never get NullReference exceptions, and this also helps make functions more self-documenting. Also use this to assert return data.