Defining specifications

clojure.spec.alpha/def binds a name to a specification, just like clojure.core/def binds a name to a value.

Binding a name means specifications are available throughout the code and in other projects if the project is included as a library.

Naming - fully qualified keywords

Specification names should use fully qualified keywords, typically using the namespace in which the specification is defined in.

Define a namespace for the page and require Clojure Spec

(ns practicalli.clojure.specifications
  (:require [clojure.spec.alpha :as spec]))

(spec/def :practicalli.clojure.specifications/number number?)

auto-resolve macro

:: double colon is the auto-resolve macro, which will pre-pend the current namespace to the specification keyword. The :: notation removes the need to edit fully qualified names should a specification be moved to a different namespace.

(spec/def ::number number?)