git clone ''

(ql:quickload :arohner.spectrum)

CircleCI Clojars Project


A library for doing static analysis of Clojure code, catching clojure.spec conform errors at compile time.

Wait what?

It's like core.typed, but it relies on clojure.spec annotations.

So it's an optional static type system?

Kind-of. It finds errors at compile time, and predicates kind of look like types. So sure.

Proving contracts ahead of time

Current Status

Developer Preview, not yet ready for any kind of use.

Current development is working towards making spectrum self-check.



In particular, spectrum aims to be fast and usable, and catching bugs. It aims to have low false positives, at the expense of potentially not catching 100% of type errors.

A tool that catches 80% of bugs that you use every day is better than a 100% tool that you don't use. Spectrum will converge on 100% correct, but won't guarantee correctness for a while.


Still under active development, so this is incomplete.

Use clojure.spec as normal. Then, at the repl:

(require '[spectrum.flow :as f])
(require '[spectrum.types :as t])

(f/infer-var #'foo)

There is also

(f/infer-form '(foo 3))

which is useful when you want to debug the signature of a form.

infer-form can optionally take a map of keywordized variables to types

(f/infer-form '(string? x) {:x #'string?})

(f/infer-form '(string? x) {:x (t/value-t 3)})




Spectrum is still very early, and not ready for production use. Current development is focused on making spectrum self-check.


Copyright © 2019 Allen Rohner

Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported