making update operators (e.g. +=) first-class functions. for issue #249

Author: JeffBezanson

j/operators.j

@@ -25,6 +25,25 @@ min(x, y) = x < y ? x : y
 
 ## definitions providing basic traits of arithmetic operators ##
 
++=(x,y)   = x+y
+-=(x,y)   = x-y
+*=(x,y)   = x*y
+.*=(x,y)  = x.*y
+/=(x,y)   = x/y
+./=(x,y)  = x./y
+//=(x,y)  = x//y
+\=(x,y)   = x\y
+.\=(x,y)  = x.\y
+^=(x,y)   = x^y
+.^=(x,y)  = x.^y
+%=(x,y)   = x%y
+|=(x,y)   = x|y
+&=(x,y)   = x&y
+$=(x,y)   = x$y
+<<=(x,y)  = x<<y
+>>=(x,y)  = x>>y
+>>>=(x,y) = x>>>y
+
 +() = 0
 *() = 1
 &() = error("zero-argument & is ambiguous")

src/julia-syntax.scm

@@ -92,7 +92,8 @@
 
 (define (expand-update-operator op lhs rhs)
   (let ((e (remove-argument-side-effects lhs)))
-    `(block ,@(cdr e) (= ,(car e) (call ,op ,(car e) ,rhs)))))
+    `(block ,@(cdr e)
+	    (= ,(car e) (call ,op ,(car e) ,rhs)))))
 
 ; (a > b > c) => (&& (call > a b) (call > b c))
 (define (expand-compare-chain e)
@@ -866,25 +867,25 @@
 		       ,body))))))
 
    ; update operators
-   (pattern-lambda (+= a b)     (expand-update-operator '+ a b))
-   (pattern-lambda (-= a b)     (expand-update-operator '- a b))
-   (pattern-lambda (*= a b)     (expand-update-operator '* a b))
-   (pattern-lambda (.*= a b)    (expand-update-operator '.* a b))
-   (pattern-lambda (/= a b)     (expand-update-operator '/ a b))
-   (pattern-lambda (./= a b)    (expand-update-operator './ a b))
-   (pattern-lambda (//= a b)    (expand-update-operator '// a b))
-   (pattern-lambda (.//= a b)   (expand-update-operator '.// a b))
-   (pattern-lambda (|\\=| a b)  (expand-update-operator '|\\| a b))
-   (pattern-lambda (|.\\=| a b) (expand-update-operator '|.\\| a b))
-   (pattern-lambda (^= a b)     (expand-update-operator '^ a b))
-   (pattern-lambda (.^= a b)    (expand-update-operator '.^ a b))
-   (pattern-lambda (%= a b)     (expand-update-operator '% a b))
-   (pattern-lambda (|\|=| a b)  (expand-update-operator '|\|| a b))
-   (pattern-lambda (&= a b)     (expand-update-operator '& a b))
-   (pattern-lambda ($= a b)     (expand-update-operator '$ a b))
-   (pattern-lambda (<<= a b)    (expand-update-operator '<< a b))
-   (pattern-lambda (>>= a b)    (expand-update-operator '>> a b))
-   (pattern-lambda (>>>= a b)   (expand-update-operator '>>> a b))
+   (pattern-lambda (+= a b)     (expand-update-operator '+= a b))
+   (pattern-lambda (-= a b)     (expand-update-operator '-= a b))
+   (pattern-lambda (*= a b)     (expand-update-operator '*= a b))
+   (pattern-lambda (.*= a b)    (expand-update-operator '.*= a b))
+   (pattern-lambda (/= a b)     (expand-update-operator '/= a b))
+   (pattern-lambda (./= a b)    (expand-update-operator './= a b))
+   (pattern-lambda (//= a b)    (expand-update-operator '//= a b))
+   (pattern-lambda (.//= a b)   (expand-update-operator './/= a b))
+   (pattern-lambda (|\\=| a b)  (expand-update-operator '|\\=| a b))
+   (pattern-lambda (|.\\=| a b) (expand-update-operator '|.\\=| a b))
+   (pattern-lambda (^= a b)     (expand-update-operator '^= a b))
+   (pattern-lambda (.^= a b)    (expand-update-operator '.^= a b))
+   (pattern-lambda (%= a b)     (expand-update-operator '%= a b))
+   (pattern-lambda (|\|=| a b)  (expand-update-operator '|\|=| a b))
+   (pattern-lambda (&= a b)     (expand-update-operator '&= a b))
+   (pattern-lambda ($= a b)     (expand-update-operator '$= a b))
+   (pattern-lambda (<<= a b)    (expand-update-operator '<<= a b))
+   (pattern-lambda (>>= a b)    (expand-update-operator '>>= a b))
+   (pattern-lambda (>>>= a b)   (expand-update-operator '>>>= a b))
 
    ;; colon
    ;;(pattern-lambda (: a (-/ :))     `(call (top RangeFrom) ,a 1))