[ANN] Pinpointer: yet another spec error reporter

[OHTA Shogo]

Hi, all

I’m happy to announce the first release of Pinpointer, yet another implementation of spec error reporter based on a precise error analysis.

- https://github.com/athos/Pinpointer

Pinpointer provides functionalities very similar to the existing spec error reporters (eg. Expound[1], Inspectable[2] etc.), that is, reporting spec errors in a more human-readable way.

[1] https://github.com/bhb/expound

[2] https://github.com/jpmonettas/inspectable

Unlike those libraries, which analyze spec errors using several heuristics, Pinpointer performs a systematic error analysis traversing a pair of the spec and the input. This makes it possible to report the error even in complicated cases where s/conformer would transform the input value, like the following:

=> (require '[pinpointer.core :as p] '[clojure.spec.alpha :as s])
=> (p/pinpointer (s/and string? (s/conformer seq) (s/* #{\a})) "aabaa")
Detected 1 spec error:
----------------------------------------------------------------------
(1/1)


    Cause: (\a \a \b \a \a)
                  ^^      
 Expected: #{\a}


   --- This comes originally from ---


 Original: "aabaa"
           ^^^^^^^
     Spec
  Applied: (s/and string? (s/conformer seq) (s/* #{\a}))


----------------------------------------------------------------------
nil
user=>




(BTW the above example is just a demo for Pinpointer's capability, and it doesn't mean to encourage you to write specs like that.)

On the other hand, one of the downsides of the library is that Pinpointer has to know in advance the behaviors of the spec macros involved in a spec form for its error analysis. Note also that, Pinpointer occasionally uses  eval under the hood (at least for now), so it’s basically intended to be used for development purpose only.

I hope you’ll like it :)

Thanks,

Shogo

[Ben Brinckerhoff]

Very cool! Excellent work.