Aave

malli powered code checking for Clojure.

Pre-alpha - highly subject to change.

“Wherever we find orderly, stable systems in Nature, we find that they are hierarchically structured, for the simple reason that without such structuring of complex systems into sub-assemblies, there could be no order and stability-except the order of a dead universr filled with a uniformly distributed gas.”

-- Arthur Koestler, The Ghost in the Machine

About

aave enables you to write inline schema definitions for your functions. It is highly configurable enabling you to choose what happens when various checks fail. It also provides utilities for common code-quality checks, such as naming conventions.

Examples / Features

In/Outstrumentation

Checks that function inputs and outputs adhere to their schemas before/after invoking function bodies.

Flags:

• :aave.core/instrument, default true
• :aave.core/outstrument, default true

Hooks:

• :aave.core/on-instrument-fail, default: throw exception
• :aave.core/on-outstrument-fail, default: throw exception

(ns example
  (:require [aave.core :refer [>defn] :as a]))

(>defn bad-return-val
  [x y]
  [int? int? => string?]
  (+ x y))

;; (bad-return-val 1 "foo") will raise `on-instrument-fail`
;; (bad-return-val 1 2) will raise `on-outstrument-fail`

Stub Generation

Causes function definitions with empty bodies to return randomly generated data instead of nil.

Flags:

• :aave.core/generate-stubs, Default: true

(ns example
  (:require [aave.core :refer [>defn] :as a]))

(>defn add
  {::a/generate-stubs true}
  [x y]
  [int? int? => int?])

;; (add 1 2) => -1

Purity Enforcement

Checks that functions that call functions with ! are also named with a !.

Flags:

• :aave.core/enforce-purity, default: true

Hooks:

• :aave.core/on-compilation-purity-fail, default: throw compile-time exception

(ns example
  (:require [aave.core :refer [>defn] :as a]))

(def counter (atom nil))

(>defn increment-counter
  "Increments the coutner and returns the old value"
  {::a/enforce-purity true
   ::a/on-purity-fail (fn [] (throw (ex-info "Purity mismatch")))}
  []
  [=> int?]
  (swap! some-atom inc)))
;; Will raise an exception. Will pass if function is named `increment-counter!`

Development

aave is an open-source project and contributions are more than welcome!

Roadmap

• Compile-time exercising of (pure) functions
• Test assertions for a namespace
• Benchmarking via ::a/benchmark true
• Consider custom exception types instead of ex-info
• Additional syntax support (eg. schema style)
• Clojurescript testing
• Config groups to save groups of settings as named groups.
• Configuration at compile time and loading via file at run time
• nrepl middleware - add ops for getting sample input and querying function metadata

Testing

clojure -Atest

Important Namespaces

• aave.core - The main "user-level" namespace. Should remain concise and focused on things that a developer would want to do from the REPL or imports that should be readily available.

• aave.code - Responsible for code generation and analysis. Provides utilities and macros for analysing and modifying code. The most important function in here is the generate macro, which is used to generate function definitions from a config map.

• aave.config - Provides the implementation of the configuration management for aave. For users, the majority of functionality should be exposed via aave.core.

• aave.syntax.* - Code parsing constructs for specific syntaxes of function declaration. Eg. ghostwheel, def-spec, etc. If you want to extend aave with support for your favorite way of declaring functions, this is the place to do it.

Inspiration

Aave borrows and builds upon ideas of many fantastic projects. Most directly, it is largely inspired by tools like ghostwheel and orchestra. Thanks to the authors and many others that have provided an amazing foundation of ideas to build upon.