parse scientific notation

compiler/can/tests/test_can.rs

@@ -174,6 +174,16 @@ mod test_can {
         assert_can_float("-0.0", -0.0);
     }
 
+    #[test]
+    fn scientific_positive() {
+        assert_can_float("5e4", 5000.0);
+    }
+
+    #[test]
+    fn scientific_negative() {
+        assert_can_float("5e-4", 0.0005);
+    }
+
     #[test]
     fn num_max() {
         assert_can_num(&(i64::MAX.to_string()), i64::MAX);

compiler/parse/src/number_literal.rs

@@ -118,6 +118,22 @@ fn chomp_number<'a>(mut bytes: &'a [u8]) -> (bool, usize) {
                 is_float = true;
                 bytes = &bytes[1..];
             }
+            b'e' => {
+                // maybe scientific notation?
+                match bytes.get(1) {
+                    Some(b'-') => {
+                        is_float = true;
+                        bytes = &bytes[2..];
+                    }
+                    Some(c) if (*c as char).is_ascii_digit() => {
+                        is_float = true;
+                        bytes = &bytes[2..];
+                    }
+                    _ => {
+                        bytes = &bytes[1..];
+                    }
+                }
+            }
             b'_' => {
                 // skip
                 bytes = &bytes[1..];