diff options
Diffstat (limited to 'src/clojure/contrib/generic/arithmetic.clj')
| -rw-r--r-- | src/clojure/contrib/generic/arithmetic.clj | 69 |
1 files changed, 47 insertions, 22 deletions
diff --git a/src/clojure/contrib/generic/arithmetic.clj b/src/clojure/contrib/generic/arithmetic.clj index 558ec37b..98d5cfef 100644 --- a/src/clojure/contrib/generic/arithmetic.clj +++ b/src/clojure/contrib/generic/arithmetic.clj @@ -1,7 +1,7 @@ ;; Generic interfaces for arithmetic operations ;; by Konrad Hinsen -;; last updated March 12, 2009 +;; last updated March 13, 2009 ;; Copyright (c) Konrad Hinsen, 2009. All rights reserved. The use ;; and distribution terms for this software are covered by the Eclipse @@ -21,7 +21,8 @@ that can be defined for any type. The minimal required implementations for a type are binary + and * plus unary - and /. Everything else is derived from these automatically. Explicit binary definitions - for - and / can be given for efficiency reasons." + for - and / can be provided for efficiency reasons." + (:use [clojure.contrib.types :only (defadt)]) (:refer-clojure :exclude [+ - * /])) ; @@ -31,26 +32,26 @@ ; (defn- nary-dispatch ([] ::nulary) - ([x] [::unary (type x)]) + ([x] (type x)) ([x y] - (let [tx (type x) - ty (type y)] - (cond (isa? tx ty) [::binary ty] - (isa? ty tx) [::binary tx] - ; Should there be clause checking if tx and ty have - ; a common ancestor? This would cover cases like - ; java.lang.Integer and java.lang.Double, which have the - ; common ancestor java.lang.Number. - :else [::binary tx ty]))) + [(type x) (type y)]) ([x y & more] ::n-ary)) ; +; Universal zero and one values +; +(defadt ::zero zero) +(defadt ::one one) + +; ; We can't use [::binary :default], so we need to define a root type ; of the type hierarcy. The derivation for Object covers all classes, ; but all non-class types will need an explicit derive clause. ; Ultimately, a macro might take care of this. ; (derive Object ::any) +(derive ::zero ::any) +(derive ::one ::any) ; ; Addition @@ -63,11 +64,17 @@ (defmethod + ::nulary [] - ::zero) + zero) -(defmethod + [::unary ::any] +(defmethod + ::any [x] x) +(defmethod + [::any ::zero] + [x y] x) + +(defmethod + [::zero ::any] + [x y] y) + (defmethod + ::n-ary [x y & more] (if more @@ -88,7 +95,13 @@ (throw (java.lang.IllegalArgumentException. "Wrong number of arguments passed"))) -(defmethod - [::binary ::any] +(defmethod - [::any ::zero] + [x y] x) + +(defmethod - [::zero ::any] + [x y] (- y)) + +(defmethod - [::any ::any] [x y] (+ x (- y))) (defmethod - ::n-ary @@ -108,11 +121,17 @@ (defmethod * ::nulary [] - ::one) + one) -(defmethod * [::unary ::any] +(defmethod * ::any [x] x) +(defmethod * [::any ::one] + [x y] x) + +(defmethod * [::one ::any] + [x y] y) + (defmethod * ::n-ary [x y & more] (if more @@ -133,7 +152,13 @@ (throw (java.lang.IllegalArgumentException. "Wrong number of arguments passed"))) -(defmethod / [::binary ::any] +(defmethod / [::any ::one] + [x y] x) + +(defmethod / [::one ::any] + [x y] (/ y)) + +(defmethod / [::any ::any] [x y] (* x (/ y))) (defmethod / ::n-ary @@ -145,15 +170,15 @@ ; ; Minimal implementations for java.lang.Number ; -(defmethod + [::binary java.lang.Number] +(defmethod + [java.lang.Number java.lang.Number] [x y] (clojure.core/+ x y)) -(defmethod - [::unary java.lang.Number] +(defmethod - java.lang.Number [x] (clojure.core/- x)) -(defmethod * [::binary java.lang.Number] +(defmethod * [java.lang.Number java.lang.Number] [x y] (clojure.core/* x y)) -(defmethod / [::unary java.lang.Number] +(defmethod / java.lang.Number [x] (clojure.core// x)) |