fix api also

src/fields/fp.rs

@@ -73,13 +73,9 @@ macro_rules! field_impl {
             }
 
             /// Converts a U256 to an Fr regardless of modulus.
-            pub fn new_mul_factor(mut a: U256) -> Option<Self> {
-                if true {
-                    a.mul(&U256::from($rsquared), &U256::from($modulus), $inv);
-                    Some($name(a))
-                } else {
-                    None
-                }
+            pub fn new_mul_factor(mut a: U256) -> Self {
+                a.mul(&U256::from($rsquared), &U256::from($modulus), $inv);
+                $name(a)
             }
 
             pub fn interpret(buf: &[u8; 64]) -> Self {

src/lib.rs

@@ -48,8 +48,7 @@ impl Fr {
     pub fn from_slice(slice: &[u8]) -> Result<Self, FieldError> {
         arith::U256::from_slice(slice)
             .map_err(|_| FieldError::InvalidSliceLength) // todo: maybe more sensful error handling
-            .and_then(|x| fields::Fr::new_mul_factor(x).ok_or(FieldError::NotMember))
-            .map(|x| Fr(x))
+            .map(|x| Fr::new_mul_factor(x))
     }
     pub fn to_big_endian(&self, slice: &mut [u8]) -> Result<(), FieldError> {
         self.0
@@ -60,8 +59,8 @@ impl Fr {
     pub fn new(val: arith::U256) -> Option<Self> {
         fields::Fr::new(val).map(|x| Fr(x))
     }
-    pub fn new_mul_factor(val: arith::U256) -> Option<Self> {
-        fields::Fr::new_mul_factor(val).map(|x| Fr(x))
+    pub fn new_mul_factor(val: arith::U256) -> Self {
+        Fr(fields::Fr::new_mul_factor(val))
     }
 }