diff options
| author | Konrad Hinsen <konrad.hinsen@laposte.net> | 2009-04-23 16:22:23 +0000 |
|---|---|---|
| committer | Konrad Hinsen <konrad.hinsen@laposte.net> | 2009-04-23 16:22:23 +0000 |
| commit | d0eeddf5d8b8bf1a03176b8212bc1610600371da (patch) | |
| tree | a6fd4d814c1cabbedcfcb8d6b5173f75ce70ddaa /src/clojure/contrib/monads.clj | |
| parent | 6c99b025c0a2b1afa6736234d3edbf7ea29b1d22 (diff) | |
monads: fixed m-plus in maybe-t
Diffstat (limited to 'src/clojure/contrib/monads.clj')
| -rw-r--r-- | src/clojure/contrib/monads.clj | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/src/clojure/contrib/monads.clj b/src/clojure/contrib/monads.clj index 1995eed5..75a20845 100644 --- a/src/clojure/contrib/monads.clj +++ b/src/clojure/contrib/monads.clj @@ -410,28 +410,28 @@ ([m nothing] (maybe-t m nothing :m-plus-default)) ([m nothing which-m-plus] (let [which-m-plus (cond (= which-m-plus :m-plus-default) - (if (= ::undefined (with-monad m m-plus)) - :m-plus-from-maybe - :m-plus-from-base) + (if (= ::undefined (with-monad m m-plus)) + :m-plus-from-maybe + :m-plus-from-base) (or (= which-m-plus :m-plus-from-base) (= which-m-plus :m-plus-from-maybe)) - which-m-plus - :else (throw (java.lang.IllegalArgumentException. - "undefined m-plus choice"))) + which-m-plus + :else + (throw (java.lang.IllegalArgumentException. + "undefined m-plus choice"))) combined-m-zero (if (= which-m-plus :m-plus-from-base) (with-monad m m-zero) (with-monad m (m-result nothing))) combined-m-plus (if (= which-m-plus :m-plus-from-base) (with-monad m m-plus) (with-monad m + ; Note: this works only if the monadic values + ; can be equality-tested. It will thus not + ; work as expected with the state monad, + ; whose monadic values are functions. (fn [& mvs] - (m-result (loop [mv (first mvs)] - (if (nil? mv) - nothing - (let [v (m-bind mv identity)] - (if (identical? v nothing) - (recur (rest mvs)) - v))))))))] + (first + (drop-while #(= % combined-m-zero) mvs)))))] (monad [m-result (with-monad m m-result) m-bind (with-monad m |