specify!

macro

since v0.0-2156

Edit

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Source docstring:

Identical to reify but mutates its first argument.

(core/defmacro specify!
  [expr & impls]
  (core/let [x (with-meta (gensym "x") {:extend :instance})]
    `(let [~x ~expr]
       (extend-type ~x ~@impls)
       ~x)))

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