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alandipert/with_conditions.clj

Last active March 18, 2016 18:26
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inline pre/post conditions macro
Raw
with_conditions.clj
(defmacro with-conditions
[conditions & body]
{:pre [(map? conditions)]}
(if-not *assert*
`(do ~@body)
(let [ret (gensym "ret")]
`(do ~@(for [pre (:pre conditions)]
`(when-not ~pre
(throw (ex-info "Precondition failed" {:pre '~pre}))))
(let [~ret (do ~@body)]
~@(for [post (:post conditions)]
`(when-not (let [~'% ~ret] ~post)
(throw (ex-info "Postcondition failed" {:post '~post}))))
~ret)))))
(defn foop [x y]
(with-conditions
{:pre [(even? x)] :post [(odd? %)]}
(+ x y)))
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