Registry for unique and re-usable specifications

So far we have just use predicate functions directly in the code examples.

Using a registry, specs can be uniquely defined across the whole project. Defining a spec gives that spec a name that has a fully qualified namespace

Use the spec specific def function to bind a new spec name and fully qualified namespace and place it in the registry

(spec/def :playing-card/suit  #{:club :diamond :heart :spade} )

(spec/conform :playing-card/suit :diamond)

(spec/def :show-cats/cat-bread #{:abyssinian :birman :chartreau :devon-rex
                        :domestic-short-hair :domestic-long-hair})

Removing specs from the registry

Named specifications can be removed from the registry by binding the name to nil.

If specification names are to be refactored, then the original name should be set to nil and evaluated, before changing the name. This will ensure stale specifications are not residing in the REPL.

Here is a named specification as an example

(spec/def ::unwanted #{:abandoned})

The specification is evaluated in the REPL (above) and currently works.

(spec/conform ::unwanted :abandoned)

Remove this specification from the registry by binding it to nil

(spec/def ::unwanted nil)

Now the specification is unavailable

(spec/conform ::unwanted :abandoned)

Registry not persistent

Restarting the REPL will loose all specification names in the registry as it is not persistent across REPL sessions.