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@tcrayford tcrayford/err.clj Secret
Last active Mar 31, 2017

What would you like to do?
(ns yeller.infrastructure.err)
(deftype Failure [f])
(defn unwrap-fail [^Failure fail]
(.f fail))
(defn fail? [potential-fail]
(isa? (class potential-fail) Failure))
(defmacro err->>
"Threads like ->>, but if
an expr returns a Failure,
run the function embedded in
the failure instead of continuing"
([x form]
(if (seq? form)
(with-meta `(~(first form) ~@(next form) ~x) (meta form))
(list form x)))
([x form & more]
`(let [result# (->> ~x ~form)]
(if (fail? result#)
(unwrap-fail result#)
(err->> result# ~@more)))))
(defmacro fail [& body]
~@(butlast body)
~(last body))))
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