1 files changed, 21 insertions, 17 deletions
diff --git a/src/eval.rs b/src/eval.rs
index 7c6ef5d..f8f4c53 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -22,28 +22,32 @@ impl Num {
         }
     }
 
+    fn powi(self, p: u64) -> Num {
+        if p == 0 {
+            return int(1);
+        }
+        if p == 1 {
+            return self;
+        }
+        if p % 2 == 0 {
+            return self.mul(self).powi(p / 2);
+        }
+        self.mul(self).powi(p / 2).mul(self)
+    }
+
     pub fn pow(self, other: Num) -> Num {
-        match (self, other) {
-            (_, Num::Int(0)) => return int(1),
-            (Num::Int(-1), Num::Int(i2)) => {
-                if i2 % 2 == 0 {
-                    return int(1);
-                } else {
-                    return int(-1);
+        match other {
+            Num::Int(i) => {
+                if let Ok(u) = u64::try_from(i) {
+                    return self.powi(u);
                 }
-            }
-            (Num::Int(0), _) => return int(0),
-            (Num::Int(1), _) => return int(1),
-            (Num::Int(i1), Num::Int(i2)) => {
-                if let Ok(u) = u32::try_from(i2) {
-                    if let Some(p) = i1.checked_pow(u) {
-                        return int(p);
-                    }
+                if let Ok(i_32) = i32::try_from(i) {
+                    return float(self.as_float().powi(i_32));
                 }
+                float(1.).div(self).powi(-i as u64)
             }
-            _ => (),
+            Num::Float(f) => float(self.as_float().powf(f)),
         }
-        float(self.as_float().powf(other.as_float()))
     }
 
     pub fn mul(self, other: Num) -> Num {