Make sci explicitly optional

[ikitommi]

Currently, if sci is a transitive dependency or is required by some other component, it will be enabled for Malli too. This is not good. Real solution would be to make installation of sci explicit, e.g. via #235:

1) explicit sci via options

(require '[malli.sci :as ms])
(require '[malli.core :as m])

(def options
  {:evaluator (ms/evaluator)
   :registry (ms/default-registry)})

(def Schema (m/schema [:fn '(fn [x] (string? x))] options))

(m/validate Schema "kikka")
; => true

2) disable via flag

, but, as it would be a breaking change (should wait for 1.0.0?), we could just add a flag wether to use sci or not.

(m/schema [:fn '(fn [x] (string? x))] {::m/enable-sci false})
; Exectution error: :malli.core/sci-not-available {:code (fn [x] (string? x))}

[ikitommi]

... and why is it not good? currently, you can't force disable sci - if you are reading schemas from 3rd party, they can attach any sci-script it, see also: babashka/sci#348