Takes a set of test/expr pairs. It evaluates each test one at a
time. If a test returns logical true, cond evaluates and returns
the value of the corresponding expr and doesn't evaluate any of the
other tests or exprs. (cond) returns nil.
(defn pos-neg-or-zero
"Determines whether or not n is positive, negative, or zero"
[n]
(cond
(< n 0) "negative"
(> n 0) "positive"
:else "zero"))
user=> (pos-neg-or-zero 5)
"positive"
user=> (pos-neg-or-zero -1)
"negative"
user=> (pos-neg-or-zero 0)
"zero"
Takes a binding-form and a set of test/expr pairs. Evaluates each tes
Source
clojure/core.clj:534
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(defmacro cond
"Takes a set of test/expr pairs. It evaluates each test one at a
time. If a test returns logical true, cond evaluates and returns
the value of the corresponding expr and doesn't evaluate any of the
other tests or exprs. (cond) returns nil."
{:added "1.0"}
[& clauses]
(when clauses
(list 'if (first clauses)
(if (next clauses)
(second clauses)
(throw (IllegalArgumentException.
"cond requires an even number of forms")))
(cons 'clojure.core/cond (next (next clauses))))))
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