1 files changed, 17 insertions, 1 deletions
diff --git a/src/boot.clj b/src/boot.clj
index c9afa590..15323ab9 100644
--- a/src/boot.clj
+++ b/src/boot.clj
@@ -2284,4 +2284,20 @@ not-every? (comp not every?))
   once, but any effects on Refs will be atomic."
   [& exprs]
   `(sync nil ~@exprs))
-      
-\ No newline at end of file
+
+(defmacro with-precision
+  "Sets the precision and rounding mode to be used for BigDecimal operations. 
+  Usage: (with-precision 10 (/ 1M 3)) 
+  or:    (with-precision 10 :rounding HALF_DOWN (/ 1M 3))
+  The rounding mode is one of CEILING, FLOOR, HALF_UP, HALF_DOWN, HALF_EVEN, 
+  UP, DOWN and UNNECESSARY; it defaults to HALF_UP."  
+  [precision & exprs]
+  (let [[body mc] 
+          (if (= (first exprs) :rounding)
+            [(rest (rest exprs))
+             (java.math.MathContext. precision 
+                                     (. clojure.lang.Reflector getStaticField java.math.RoundingMode (name (second exprs))))]
+            [exprs
+             (java.math.MathContext. precision)])]
+    `(binding [*math-context* ~mc]
+       ~@body)))
+\ No newline at end of file