diff --git a/.gitignore b/.gitignore
index 140811c2..e884ce0f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,6 @@ target/
 Cargo.lock
 .vscode/
 .cargo/
-doc/book/
\ No newline at end of file
+doc/book/
+before
+after
diff --git a/doc/src/language/loop.md b/doc/src/language/loop.md
index b92c3f7e..e625082a 100644
--- a/doc/src/language/loop.md
+++ b/doc/src/language/loop.md
@@ -12,7 +12,7 @@ Like C, `continue` can be used to skip to the next iteration, by-passing all fol
 let x = 10;
 
 loop {
-    x = x - 1;
+    x -= 1;
 
     if x > 5 { continue; }  // skip to the next iteration
 
diff --git a/doc/src/language/while.md b/doc/src/language/while.md
index e912175e..5b7a5ac8 100644
--- a/doc/src/language/while.md
+++ b/doc/src/language/while.md
@@ -12,7 +12,7 @@ Like C, `continue` can be used to skip to the next iteration, by-passing all fol
 let x = 10;
 
 while x > 0 {
-    x = x - 1;
+    x -= 1;
     if x < 6 { continue; }  // skip to the next iteration
     print(x);
     if x == 5 { break; }    // break out of while loop
diff --git a/src/api.rs b/src/api.rs
index 42805fa3..5df12aba 100644
--- a/src/api.rs
+++ b/src/api.rs
@@ -1046,8 +1046,8 @@ impl Engine {
     /// let mut scope = Scope::new();
     /// scope.push("x", 40_i64);
     ///
-    /// assert_eq!(engine.eval_with_scope::<i64>(&mut scope, "x = x + 2; x")?, 42);
-    /// assert_eq!(engine.eval_with_scope::<i64>(&mut scope, "x = x + 2; x")?, 44);
+    /// assert_eq!(engine.eval_with_scope::<i64>(&mut scope, "x += 2; x")?, 42);
+    /// assert_eq!(engine.eval_with_scope::<i64>(&mut scope, "x += 2; x")?, 44);
     ///
     /// // The variable in the scope is modified
     /// assert_eq!(scope.get_value::<i64>("x").expect("variable x should exist"), 44);
@@ -1160,7 +1160,7 @@ impl Engine {
     /// scope.push("x", 40_i64);
     ///
     /// // Compile a script to an AST and store it for later evaluation
-    /// let ast = engine.compile("x = x + 2; x")?;
+    /// let ast = engine.compile("x += 2; x")?;
     ///
     /// // Evaluate it
     /// assert_eq!(engine.eval_ast_with_scope::<i64>(&mut scope, &ast)?, 42);
diff --git a/src/engine.rs b/src/engine.rs
index 50e30837..937c01e8 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -11,7 +11,7 @@ use crate::parser::{Expr, FnAccess, ImmutableString, ReturnType, ScriptFnDef, St
 use crate::r#unsafe::unsafe_cast_var_name_to_lifetime;
 use crate::result::EvalAltResult;
 use crate::scope::{EntryType as ScopeEntryType, Scope};
-use crate::token::{is_valid_identifier, Position};
+use crate::token::Position;
 use crate::utils::StaticVec;
 
 #[cfg(not(feature = "no_float"))]
@@ -22,6 +22,7 @@ use crate::stdlib::{
     borrow::Cow,
     boxed::Box,
     collections::{HashMap, HashSet},
+    convert::TryFrom,
     format,
     iter::{empty, once},
     mem,
@@ -1735,6 +1736,7 @@ impl Engine {
                         let expr = args_expr.get(0);
                         let arg_value =
                             self.eval_expr(scope, mods, state, lib, this_ptr, expr, level)?;
+
                         return arg_value
                             .take_immutable_string()
                             .map_err(|typ| {
@@ -1744,17 +1746,9 @@ impl Engine {
                                     expr.position(),
                                 ))
                             })
-                            .and_then(|s| {
-                                if is_valid_identifier(s.chars()) {
-                                    Ok(s)
-                                } else {
-                                    Err(Box::new(EvalAltResult::ErrorFunctionNotFound(
-                                        s.to_string(),
-                                        expr.position(),
-                                    )))
-                                }
-                            })
-                            .map(|s| FnPtr::from(s).into());
+                            .and_then(|s| FnPtr::try_from(s))
+                            .map(Into::<Dynamic>::into)
+                            .map_err(|err| err.new_position(*pos));
                     }
                 }
 
diff --git a/src/fn_native.rs b/src/fn_native.rs
index b4c57324..8bfc241d 100644
--- a/src/fn_native.rs
+++ b/src/fn_native.rs
@@ -4,9 +4,10 @@ use crate::module::Module;
 use crate::parser::ScriptFnDef;
 use crate::plugin::PluginFunction;
 use crate::result::EvalAltResult;
+use crate::token::{is_valid_identifier, Position};
 use crate::utils::ImmutableString;
 
-use crate::stdlib::{boxed::Box, fmt, rc::Rc, sync::Arc};
+use crate::stdlib::{boxed::Box, convert::TryFrom, fmt, rc::Rc, sync::Arc};
 
 /// Trait that maps to `Send + Sync` only under the `sync` feature.
 #[cfg(feature = "sync")]
@@ -53,6 +54,10 @@ pub type FnCallArgs<'a> = [&'a mut Dynamic];
 pub struct FnPtr(ImmutableString);
 
 impl FnPtr {
+    /// Create a new function pointer.
+    pub(crate) fn new<S: Into<ImmutableString>>(name: S) -> Self {
+        Self(name.into())
+    }
     /// Get the name of the function.
     pub fn fn_name(&self) -> &str {
         self.get_fn_name().as_ref()
@@ -73,9 +78,36 @@ impl fmt::Display for FnPtr {
     }
 }
 
-impl<S: Into<ImmutableString>> From<S> for FnPtr {
-    fn from(value: S) -> Self {
-        Self(value.into())
+impl TryFrom<ImmutableString> for FnPtr {
+    type Error = Box<EvalAltResult>;
+
+    fn try_from(value: ImmutableString) -> Result<Self, Self::Error> {
+        if is_valid_identifier(value.chars()) {
+            Ok(Self(value))
+        } else {
+            Err(Box::new(EvalAltResult::ErrorFunctionNotFound(
+                value.to_string(),
+                Position::none(),
+            )))
+        }
+    }
+}
+
+impl TryFrom<String> for FnPtr {
+    type Error = Box<EvalAltResult>;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        let s: ImmutableString = value.into();
+        Self::try_from(s)
+    }
+}
+
+impl TryFrom<&str> for FnPtr {
+    type Error = Box<EvalAltResult>;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        let s: ImmutableString = value.into();
+        Self::try_from(s)
     }
 }
 
diff --git a/src/lib.rs b/src/lib.rs
index 391a71f7..064e0c89 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -102,7 +102,7 @@ mod utils;
 pub use any::Dynamic;
 pub use engine::Engine;
 pub use error::{ParseError, ParseErrorType};
-pub use fn_native::IteratorFn;
+pub use fn_native::{FnPtr, IteratorFn};
 pub use fn_register::{RegisterFn, RegisterPlugin, RegisterResultFn};
 pub use module::Module;
 pub use parser::{ImmutableString, AST, INT};
diff --git a/src/serde/de.rs b/src/serde/de.rs
index 82910073..88533718 100644
--- a/src/serde/de.rs
+++ b/src/serde/de.rs
@@ -7,7 +7,10 @@ use crate::result::EvalAltResult;
 use crate::token::Position;
 use crate::utils::ImmutableString;
 
-use serde::de::{DeserializeSeed, Deserializer, Error, MapAccess, SeqAccess, Visitor};
+use serde::de::{
+    DeserializeSeed, Deserializer, EnumAccess, Error, IntoDeserializer, MapAccess, SeqAccess,
+    VariantAccess, Visitor,
+};
 use serde::Deserialize;
 
 #[cfg(not(feature = "no_index"))]
@@ -49,6 +52,20 @@ impl<'de> DynamicDeserializer<'de> {
             Position::none(),
         )))
     }
+    fn deserialize_int<V: Visitor<'de>>(
+        &mut self,
+        v: crate::INT,
+        visitor: V,
+    ) -> Result<V::Value, Box<EvalAltResult>> {
+        #[cfg(not(feature = "only_i32"))]
+        {
+            visitor.visit_i64(v)
+        }
+        #[cfg(feature = "only_i32")]
+        {
+            visitor.visit_i32(v)
+        }
+    }
 }
 
 /// Deserialize a `Dynamic` value into a Rust type that implements `serde::Deserialize`.
@@ -159,51 +176,87 @@ impl<'de> Deserializer<'de> for &mut DynamicDeserializer<'de> {
     }
 
     fn deserialize_i8<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<i8>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_i8(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else {
+            self.value
+                .downcast_ref::<i8>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_i8(x))
+        }
     }
 
     fn deserialize_i16<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<i16>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_i16(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else {
+            self.value
+                .downcast_ref::<i16>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_i16(x))
+        }
     }
 
     fn deserialize_i32<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<i32>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_i32(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else if cfg!(feature = "only_i32") {
+            self.type_error()
+        } else {
+            self.value
+                .downcast_ref::<i32>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_i32(x))
+        }
     }
 
     fn deserialize_i64<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<i64>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_i64(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else if cfg!(not(feature = "only_i32")) {
+            self.type_error()
+        } else {
+            self.value
+                .downcast_ref::<i64>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_i64(x))
+        }
     }
 
     fn deserialize_u8<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<u8>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_u8(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else {
+            self.value
+                .downcast_ref::<u8>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_u8(x))
+        }
     }
 
     fn deserialize_u16<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<u16>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_u16(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else {
+            self.value
+                .downcast_ref::<u16>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_u16(x))
+        }
     }
 
     fn deserialize_u32<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<u32>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_u32(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else {
+            self.value
+                .downcast_ref::<u32>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_u32(x))
+        }
     }
 
     fn deserialize_u64<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
-        self.value
-            .downcast_ref::<u64>()
-            .map_or_else(|| self.type_error(), |&x| visitor.visit_u64(x))
+        if let Ok(v) = self.value.as_int() {
+            self.deserialize_int(v, visitor)
+        } else {
+            self.value
+                .downcast_ref::<u64>()
+                .map_or_else(|| self.type_error(), |&x| visitor.visit_u64(x))
+        }
     }
 
     fn deserialize_f32<V: Visitor<'de>>(self, visitor: V) -> Result<V::Value, Box<EvalAltResult>> {
@@ -334,9 +387,30 @@ impl<'de> Deserializer<'de> for &mut DynamicDeserializer<'de> {
         self,
         _name: &'static str,
         _variants: &'static [&'static str],
-        _: V,
+        visitor: V,
     ) -> Result<V::Value, Box<EvalAltResult>> {
-        self.type_error()
+        if let Ok(s) = self.value.as_str() {
+            visitor.visit_enum(s.into_deserializer())
+        } else {
+            #[cfg(not(feature = "no_object"))]
+            if let Some(map) = self.value.downcast_ref::<Map>() {
+                let mut iter = map.iter();
+                let first = iter.next();
+                let second = iter.next();
+                if let (Some((key, value)), None) = (first, second) {
+                    visitor.visit_enum(EnumDeserializer {
+                        tag: &key,
+                        content: DynamicDeserializer::from_dynamic(value),
+                    })
+                } else {
+                    self.type_error()
+                }
+            } else {
+                self.type_error()
+            }
+            #[cfg(feature = "no_object")]
+            return self.type_error();
+        }
     }
 
     fn deserialize_identifier<V: Visitor<'de>>(
@@ -444,3 +518,57 @@ where
         ))
     }
 }
+
+#[cfg(not(feature = "no_object"))]
+struct EnumDeserializer<'t, 'de: 't> {
+    tag: &'t str,
+    content: DynamicDeserializer<'de>,
+}
+
+#[cfg(not(feature = "no_object"))]
+impl<'t, 'de> EnumAccess<'de> for EnumDeserializer<'t, 'de> {
+    type Error = Box<EvalAltResult>;
+    type Variant = Self;
+
+    fn variant_seed<V>(self, seed: V) -> Result<(V::Value, Self::Variant), Self::Error>
+    where
+        V: DeserializeSeed<'de>,
+    {
+        seed.deserialize(self.tag.into_deserializer())
+            .map(|v| (v, self))
+    }
+}
+
+#[cfg(not(feature = "no_object"))]
+impl<'t, 'de> VariantAccess<'de> for EnumDeserializer<'t, 'de> {
+    type Error = Box<EvalAltResult>;
+
+    fn unit_variant(mut self) -> Result<(), Self::Error> {
+        Deserialize::deserialize(&mut self.content)
+    }
+
+    fn newtype_variant_seed<T>(mut self, seed: T) -> Result<T::Value, Self::Error>
+    where
+        T: DeserializeSeed<'de>,
+    {
+        seed.deserialize(&mut self.content)
+    }
+
+    fn tuple_variant<V>(mut self, len: usize, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        self.content.deserialize_tuple(len, visitor)
+    }
+
+    fn struct_variant<V>(
+        mut self,
+        fields: &'static [&'static str],
+        visitor: V,
+    ) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        self.content.deserialize_struct("", fields, visitor)
+    }
+}
diff --git a/src/serde/ser.rs b/src/serde/ser.rs
index 1477da2d..181573b0 100644
--- a/src/serde/ser.rs
+++ b/src/serde/ser.rs
@@ -103,10 +103,16 @@ impl Serializer for &mut DynamicSerializer {
     type SerializeSeq = DynamicSerializer;
     type SerializeTuple = DynamicSerializer;
     type SerializeTupleStruct = DynamicSerializer;
-    type SerializeTupleVariant = DynamicSerializer;
+    #[cfg(not(any(feature = "no_object", feature = "no_index")))]
+    type SerializeTupleVariant = TupleVariantSerializer;
+    #[cfg(any(feature = "no_object", feature = "no_index"))]
+    type SerializeTupleVariant = serde::ser::Impossible<Dynamic, Box<EvalAltResult>>;
     type SerializeMap = DynamicSerializer;
     type SerializeStruct = DynamicSerializer;
-    type SerializeStructVariant = DynamicSerializer;
+    #[cfg(not(feature = "no_object"))]
+    type SerializeStructVariant = StructVariantSerializer;
+    #[cfg(feature = "no_object")]
+    type SerializeStructVariant = serde::ser::Impossible<Dynamic, Box<EvalAltResult>>;
 
     fn serialize_bool(self, v: bool) -> Result<Self::Ok, Box<EvalAltResult>> {
         Ok(v.into())
@@ -162,7 +168,7 @@ impl Serializer for &mut DynamicSerializer {
         #[cfg(not(feature = "only_i32"))]
         return self.serialize_i64(i64::from(v));
         #[cfg(feature = "only_i32")]
-        if v > i32::MAX as u64 {
+        if v > i32::MAX as u32 {
             return Ok(Dynamic::from(v));
         } else {
             return self.serialize_i32(v as i32);
@@ -244,10 +250,20 @@ impl Serializer for &mut DynamicSerializer {
         self,
         _name: &'static str,
         _variant_index: u32,
-        _variant: &'static str,
+        variant: &'static str,
         value: &T,
     ) -> Result<Self::Ok, Box<EvalAltResult>> {
-        value.serialize(&mut *self)
+        #[cfg(not(feature = "no_object"))]
+        {
+            let content = to_dynamic(value)?;
+            make_variant(variant, content)
+        }
+        #[cfg(feature = "no_object")]
+        return Err(Box::new(EvalAltResult::ErrorMismatchOutputType(
+            "Dynamic".into(),
+            "map".into(),
+            Position::none(),
+        )));
     }
 
     fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, Box<EvalAltResult>> {
@@ -277,10 +293,26 @@ impl Serializer for &mut DynamicSerializer {
         self,
         _name: &'static str,
         _variant_index: u32,
-        _variant: &'static str,
+        variant: &'static str,
         len: usize,
     ) -> Result<Self::SerializeTupleVariant, Box<EvalAltResult>> {
-        self.serialize_seq(Some(len))
+        #[cfg(not(any(feature = "no_object", feature = "no_index")))]
+        return Ok(TupleVariantSerializer {
+            variant,
+            array: Array::with_capacity(len),
+        });
+        #[cfg(any(feature = "no_object", feature = "no_index"))]
+        {
+            #[cfg(feature = "no_object")]
+            let err_type = "map";
+            #[cfg(not(feature = "no_object"))]
+            let err_type = "array";
+            Err(Box::new(EvalAltResult::ErrorMismatchOutputType(
+                "Dynamic".into(),
+                err_type.into(),
+                Position::none(),
+            )))
+        }
     }
 
     fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, Box<EvalAltResult>> {
@@ -306,10 +338,20 @@ impl Serializer for &mut DynamicSerializer {
         self,
         _name: &'static str,
         _variant_index: u32,
-        _variant: &'static str,
+        variant: &'static str,
         len: usize,
     ) -> Result<Self::SerializeStructVariant, Box<EvalAltResult>> {
-        self.serialize_map(Some(len))
+        #[cfg(not(feature = "no_object"))]
+        return Ok(StructVariantSerializer {
+            variant,
+            map: Map::with_capacity(len),
+        });
+        #[cfg(feature = "no_object")]
+        return Err(Box::new(EvalAltResult::ErrorMismatchOutputType(
+            "Dynamic".into(),
+            "map".into(),
+            Position::none(),
+        )));
     }
 }
 
@@ -395,33 +437,6 @@ impl SerializeTupleStruct for DynamicSerializer {
     }
 }
 
-impl SerializeTupleVariant for DynamicSerializer {
-    type Ok = Dynamic;
-    type Error = Box<EvalAltResult>;
-
-    fn serialize_field<T: ?Sized + Serialize>(
-        &mut self,
-        value: &T,
-    ) -> Result<(), Box<EvalAltResult>> {
-        #[cfg(not(feature = "no_index"))]
-        {
-            let value = value.serialize(&mut *self)?;
-            let arr = self.value.downcast_mut::<Array>().unwrap();
-            arr.push(value);
-            Ok(())
-        }
-        #[cfg(feature = "no_index")]
-        unreachable!()
-    }
-
-    fn end(self) -> Result<Self::Ok, Box<EvalAltResult>> {
-        #[cfg(not(feature = "no_index"))]
-        return Ok(self.value);
-        #[cfg(feature = "no_index")]
-        unreachable!()
-    }
-}
-
 impl SerializeMap for DynamicSerializer {
     type Ok = Dynamic;
     type Error = Box<EvalAltResult>;
@@ -520,7 +535,39 @@ impl SerializeStruct for DynamicSerializer {
     }
 }
 
-impl SerializeStructVariant for DynamicSerializer {
+#[cfg(not(any(feature = "no_object", feature = "no_index")))]
+pub struct TupleVariantSerializer {
+    variant: &'static str,
+    array: Array,
+}
+
+#[cfg(not(any(feature = "no_object", feature = "no_index")))]
+impl SerializeTupleVariant for TupleVariantSerializer {
+    type Ok = Dynamic;
+    type Error = Box<EvalAltResult>;
+
+    fn serialize_field<T: ?Sized + Serialize>(
+        &mut self,
+        value: &T,
+    ) -> Result<(), Box<EvalAltResult>> {
+        let value = to_dynamic(value)?;
+        self.array.push(value);
+        Ok(())
+    }
+
+    fn end(self) -> Result<Self::Ok, Box<EvalAltResult>> {
+        make_variant(self.variant, self.array.into())
+    }
+}
+
+#[cfg(not(feature = "no_object"))]
+pub struct StructVariantSerializer {
+    variant: &'static str,
+    map: Map,
+}
+
+#[cfg(not(feature = "no_object"))]
+impl SerializeStructVariant for StructVariantSerializer {
     type Ok = Dynamic;
     type Error = Box<EvalAltResult>;
 
@@ -529,21 +576,19 @@ impl SerializeStructVariant for DynamicSerializer {
         key: &'static str,
         value: &T,
     ) -> Result<(), Box<EvalAltResult>> {
-        #[cfg(not(feature = "no_object"))]
-        {
-            let value = value.serialize(&mut *self)?;
-            let map = self.value.downcast_mut::<Map>().unwrap();
-            map.insert(key.into(), value);
-            Ok(())
-        }
-        #[cfg(feature = "no_object")]
-        unreachable!()
+        let value = to_dynamic(value)?;
+        self.map.insert(key.into(), value);
+        Ok(())
     }
 
     fn end(self) -> Result<Self::Ok, Box<EvalAltResult>> {
-        #[cfg(not(feature = "no_object"))]
-        return Ok(self.value);
-        #[cfg(feature = "no_object")]
-        unreachable!()
+        make_variant(self.variant, self.map.into())
     }
 }
+
+#[cfg(not(feature = "no_object"))]
+fn make_variant(variant: &'static str, value: Dynamic) -> Result<Dynamic, Box<EvalAltResult>> {
+    let mut map = Map::with_capacity(1);
+    map.insert(variant.into(), value);
+    Ok(map.into())
+}
diff --git a/tests/call_fn.rs b/tests/call_fn.rs
index 690577ce..715fbc87 100644
--- a/tests/call_fn.rs
+++ b/tests/call_fn.rs
@@ -32,7 +32,7 @@ fn test_call_fn() -> Result<(), Box<EvalAltResult>> {
                 x + y
             }
             fn hello(x) {
-                x = x * foo;
+                x *= foo;
                 foo = 1;
                 x
             }
diff --git a/tests/looping.rs b/tests/looping.rs
index 3a4804ce..951f8cd7 100644
--- a/tests/looping.rs
+++ b/tests/looping.rs
@@ -14,7 +14,7 @@ fn test_loop() -> Result<(), Box<EvalAltResult>> {
 					if i < 10 {
 						i += 1;
 						if x > 20 { continue; }
-						x = x + i;
+						x += i;
 					} else {
 						break;
 					}
diff --git a/tests/serde.rs b/tests/serde.rs
index 82ec330b..005e4e8c 100644
--- a/tests/serde.rs
+++ b/tests/serde.rs
@@ -10,25 +10,33 @@ use rhai::Map;
 
 #[test]
 fn test_serde_ser_primary_types() -> Result<(), Box<EvalAltResult>> {
-    assert_eq!(
-        to_dynamic(42_u64)?.type_name(),
-        std::any::type_name::<INT>()
-    );
-    assert_eq!(to_dynamic(u64::MAX)?.type_name(), "u64");
-    assert_eq!(
-        to_dynamic(42 as INT)?.type_name(),
-        std::any::type_name::<INT>()
-    );
-    assert_eq!(to_dynamic(true)?.type_name(), "bool");
-    assert_eq!(to_dynamic(())?.type_name(), "()");
+    assert!(to_dynamic(42_u64)?.is::<INT>());
+    assert!(to_dynamic(u64::MAX)?.is::<u64>());
+    assert!(to_dynamic(42 as INT)?.is::<INT>());
+    assert!(to_dynamic(true)?.is::<bool>());
+    assert!(to_dynamic(())?.is::<()>());
 
     #[cfg(not(feature = "no_float"))]
     {
-        assert_eq!(to_dynamic(123.456_f64)?.type_name(), "f64");
-        assert_eq!(to_dynamic(123.456_f32)?.type_name(), "f32");
+        assert!(to_dynamic(123.456_f64)?.is::<f64>());
+        assert!(to_dynamic(123.456_f32)?.is::<f32>());
     }
 
-    assert_eq!(to_dynamic("hello".to_string())?.type_name(), "string");
+    assert!(to_dynamic("hello".to_string())?.is::<String>());
+
+    Ok(())
+}
+
+#[test]
+fn test_serde_ser_integer_types() -> Result<(), Box<EvalAltResult>> {
+    assert!(to_dynamic(42_i8)?.is::<INT>());
+    assert!(to_dynamic(42_i16)?.is::<INT>());
+    assert!(to_dynamic(42_i32)?.is::<INT>());
+    assert!(to_dynamic(42_i64)?.is::<INT>());
+    assert!(to_dynamic(42_u8)?.is::<INT>());
+    assert!(to_dynamic(42_u16)?.is::<INT>());
+    assert!(to_dynamic(42_u32)?.is::<INT>());
+    assert!(to_dynamic(42_u64)?.is::<INT>());
 
     Ok(())
 }
@@ -40,7 +48,7 @@ fn test_serde_ser_array() -> Result<(), Box<EvalAltResult>> {
 
     let d = to_dynamic(arr)?;
     assert!(d.is::<Array>());
-    assert_eq!(d.cast::<Array>().len(), 4);
+    assert_eq!(4, d.cast::<Array>().len());
 
     Ok(())
 }
@@ -73,14 +81,226 @@ fn test_serde_ser_struct() -> Result<(), Box<EvalAltResult>> {
     assert!(d.is::<Map>());
 
     let mut map = d.cast::<Map>();
-    let mut obj = map.remove("obj").unwrap().cast::<Map>();
-    let mut seq = map.remove("seq").unwrap().cast::<Array>();
+    let obj = map.remove("obj").unwrap().cast::<Map>();
+    let seq = map.remove("seq").unwrap().cast::<Array>();
 
-    assert_eq!(obj.remove("a").unwrap().cast::<INT>(), 123);
-    assert!(obj.remove("b").unwrap().cast::<bool>());
-    assert_eq!(map.remove("int").unwrap().cast::<INT>(), 42);
+    assert_eq!(Ok(123), obj["a"].as_int());
+    assert!(obj["b"].as_bool().unwrap());
+    assert_eq!(Ok(42), map["int"].as_int());
     assert_eq!(seq.len(), 3);
-    assert_eq!(seq.remove(1).cast::<String>(), "kitty");
+    assert_eq!(Ok("kitty"), seq[1].as_str());
+
+    Ok(())
+}
+
+#[test]
+fn test_serde_ser_unit_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Serialize)]
+    enum MyEnum {
+        VariantFoo,
+        VariantBar,
+    }
+
+    let d = to_dynamic(MyEnum::VariantFoo)?;
+    assert_eq!(Ok("VariantFoo"), d.as_str());
+
+    let d = to_dynamic(MyEnum::VariantBar)?;
+    assert_eq!(Ok("VariantBar"), d.as_str());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_ser_externally_tagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Serialize)]
+    enum MyEnum {
+        VariantUnit,
+        #[cfg(not(feature = "no_index"))]
+        VariantUnitTuple(),
+        VariantNewtype(i32),
+        #[cfg(not(feature = "no_index"))]
+        VariantTuple(i32, i32),
+        VariantEmptyStruct {},
+        VariantStruct {
+            a: i32,
+        },
+    }
+
+    {
+        assert_eq!(Ok("VariantUnit"), to_dynamic(MyEnum::VariantUnit)?.as_str());
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let mut map = to_dynamic(MyEnum::VariantUnitTuple())?.cast::<Map>();
+        let content = map.remove("VariantUnitTuple").unwrap().cast::<Array>();
+        assert!(map.is_empty());
+        assert!(content.is_empty());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantNewtype(123))?.cast::<Map>();
+        let content = map.remove("VariantNewtype").unwrap();
+        assert!(map.is_empty());
+        assert_eq!(Ok(123), content.as_int());
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let mut map = to_dynamic(MyEnum::VariantTuple(123, 456))?.cast::<Map>();
+        let content = map.remove("VariantTuple").unwrap().cast::<Array>();
+        assert!(map.is_empty());
+        assert_eq!(2, content.len());
+        assert_eq!(Ok(123), content[0].as_int());
+        assert_eq!(Ok(456), content[1].as_int());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantEmptyStruct {})?.cast::<Map>();
+        let map_inner = map.remove("VariantEmptyStruct").unwrap().cast::<Map>();
+        assert!(map.is_empty());
+        assert!(map_inner.is_empty());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantStruct { a: 123 })?.cast::<Map>();
+        let mut map_inner = map.remove("VariantStruct").unwrap().cast::<Map>();
+        assert!(map.is_empty());
+        assert_eq!(Ok(123), map_inner.remove("a").unwrap().as_int());
+        assert!(map_inner.is_empty());
+    }
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_ser_internally_tagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Serialize)]
+    #[serde(tag = "tag")]
+    enum MyEnum {
+        VariantEmptyStruct {},
+        VariantStruct { a: i32 },
+    }
+
+    let mut map = to_dynamic(MyEnum::VariantEmptyStruct {})?.cast::<Map>();
+    assert_eq!(
+        Ok("VariantEmptyStruct"),
+        map.remove("tag").unwrap().as_str()
+    );
+    assert!(map.is_empty());
+
+    let mut map = to_dynamic(MyEnum::VariantStruct { a: 123 })?.cast::<Map>();
+    assert_eq!(Ok("VariantStruct"), map.remove("tag").unwrap().as_str());
+    assert_eq!(Ok(123), map.remove("a").unwrap().as_int());
+    assert!(map.is_empty());
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_ser_adjacently_tagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Serialize)]
+    #[serde(tag = "tag", content = "content")]
+    enum MyEnum {
+        VariantUnit,
+        #[cfg(not(feature = "no_index"))]
+        VariantUnitTuple(),
+        VariantNewtype(i32),
+        #[cfg(not(feature = "no_index"))]
+        VariantTuple(i32, i32),
+        VariantEmptyStruct {},
+        VariantStruct {
+            a: i32,
+        },
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantUnit)?.cast::<Map>();
+        assert_eq!(Ok("VariantUnit"), map.remove("tag").unwrap().as_str());
+        assert!(map.is_empty());
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let mut map = to_dynamic(MyEnum::VariantUnitTuple())?.cast::<Map>();
+        assert_eq!(Ok("VariantUnitTuple"), map.remove("tag").unwrap().as_str());
+        let content = map.remove("content").unwrap().cast::<Array>();
+        assert!(map.is_empty());
+        assert!(content.is_empty());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantNewtype(123))?.cast::<Map>();
+        assert_eq!(Ok("VariantNewtype"), map.remove("tag").unwrap().as_str());
+        let content = map.remove("content").unwrap();
+        assert!(map.is_empty());
+        assert_eq!(Ok(123), content.as_int());
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let mut map = to_dynamic(MyEnum::VariantTuple(123, 456))?.cast::<Map>();
+        assert_eq!(Ok("VariantTuple"), map.remove("tag").unwrap().as_str());
+        let content = map.remove("content").unwrap().cast::<Array>();
+        assert!(map.is_empty());
+        assert_eq!(2, content.len());
+        assert_eq!(Ok(123), content[0].as_int());
+        assert_eq!(Ok(456), content[1].as_int());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantEmptyStruct {})?.cast::<Map>();
+        assert_eq!(
+            Ok("VariantEmptyStruct"),
+            map.remove("tag").unwrap().as_str()
+        );
+        let map_inner = map.remove("content").unwrap().cast::<Map>();
+        assert!(map.is_empty());
+        assert!(map_inner.is_empty());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantStruct { a: 123 })?.cast::<Map>();
+        assert_eq!(Ok("VariantStruct"), map.remove("tag").unwrap().as_str());
+        let mut map_inner = map.remove("content").unwrap().cast::<Map>();
+        assert!(map.is_empty());
+        assert_eq!(Ok(123), map_inner.remove("a").unwrap().as_int());
+        assert!(map_inner.is_empty());
+    }
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_ser_untagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Serialize)]
+    #[serde(untagged)]
+    enum MyEnum {
+        VariantEmptyStruct {},
+        VariantStruct1 { a: i32 },
+        VariantStruct2 { b: i32 },
+    }
+
+    {
+        let map = to_dynamic(MyEnum::VariantEmptyStruct {})?.cast::<Map>();
+        assert!(map.is_empty());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantStruct1 { a: 123 })?.cast::<Map>();
+        assert_eq!(Ok(123), map.remove("a").unwrap().as_int());
+        assert!(map.is_empty());
+    }
+
+    {
+        let mut map = to_dynamic(MyEnum::VariantStruct2 { b: 123 })?.cast::<Map>();
+        assert_eq!(Ok(123), map.remove("b").unwrap().as_int());
+        assert!(map.is_empty());
+    }
 
     Ok(())
 }
@@ -106,6 +326,20 @@ fn test_serde_de_primary_types() -> Result<(), Box<EvalAltResult>> {
     Ok(())
 }
 
+#[test]
+fn test_serde_de_integer_types() -> Result<(), Box<EvalAltResult>> {
+    assert_eq!(42_i8, from_dynamic(&Dynamic::from(42 as INT))?);
+    assert_eq!(42_i16, from_dynamic(&Dynamic::from(42 as INT))?);
+    assert_eq!(42_i32, from_dynamic(&Dynamic::from(42 as INT))?);
+    assert_eq!(42_i64, from_dynamic(&Dynamic::from(42 as INT))?);
+    assert_eq!(42_u8, from_dynamic(&Dynamic::from(42 as INT))?);
+    assert_eq!(42_u16, from_dynamic(&Dynamic::from(42 as INT))?);
+    assert_eq!(42_u32, from_dynamic(&Dynamic::from(42 as INT))?);
+    assert_eq!(42_u64, from_dynamic(&Dynamic::from(42 as INT))?);
+
+    Ok(())
+}
+
 #[test]
 #[cfg(not(feature = "no_index"))]
 fn test_serde_de_array() -> Result<(), Box<EvalAltResult>> {
@@ -190,3 +424,261 @@ fn test_serde_de_script() -> Result<(), Box<EvalAltResult>> {
 
     Ok(())
 }
+
+#[test]
+fn test_serde_de_unit_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Debug, PartialEq, Deserialize)]
+    enum MyEnum {
+        VariantFoo,
+        VariantBar,
+    }
+
+    {
+        let d = Dynamic::from("VariantFoo".to_string());
+        assert_eq!(MyEnum::VariantFoo, from_dynamic(&d)?);
+    }
+
+    {
+        let d = Dynamic::from("VariantBar".to_string());
+        assert_eq!(MyEnum::VariantBar, from_dynamic(&d)?);
+    }
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_de_externally_tagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Debug, PartialEq, Deserialize)]
+    #[serde(deny_unknown_fields)]
+    enum MyEnum {
+        VariantUnit,
+        #[cfg(not(feature = "no_index"))]
+        VariantUnitTuple(),
+        VariantNewtype(i32),
+        #[cfg(not(feature = "no_index"))]
+        VariantTuple(i32, i32),
+        VariantEmptyStruct {},
+        VariantStruct {
+            a: i32,
+        },
+    }
+
+    {
+        let d = Dynamic::from("VariantUnit".to_string());
+        assert_eq!(MyEnum::VariantUnit, from_dynamic(&d).unwrap());
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let array: Array = vec![];
+        let mut map_outer = Map::new();
+        map_outer.insert("VariantUnitTuple".into(), array.into());
+        assert_eq!(
+            MyEnum::VariantUnitTuple(),
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    {
+        let mut map_outer = Map::new();
+        map_outer.insert("VariantNewtype".into(), (123 as INT).into());
+        assert_eq!(
+            MyEnum::VariantNewtype(123),
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let array: Array = vec![(123 as INT).into(), (456 as INT).into()];
+        let mut map_outer = Map::new();
+        map_outer.insert("VariantTuple".into(), array.into());
+        assert_eq!(
+            MyEnum::VariantTuple(123, 456),
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    {
+        let map_inner = Map::new();
+        let mut map_outer = Map::new();
+        map_outer.insert("VariantEmptyStruct".into(), map_inner.into());
+        assert_eq!(
+            MyEnum::VariantEmptyStruct {},
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    {
+        let mut map_inner = Map::new();
+        map_inner.insert("a".into(), (123 as INT).into());
+        let mut map_outer = Map::new();
+        map_outer.insert("VariantStruct".into(), map_inner.into());
+        assert_eq!(
+            MyEnum::VariantStruct { a: 123 },
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_de_internally_tagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Debug, PartialEq, Deserialize)]
+    #[serde(tag = "tag", deny_unknown_fields)]
+    enum MyEnum {
+        VariantEmptyStruct {},
+        VariantStruct { a: i32 },
+    }
+
+    {
+        let mut map = Map::new();
+        map.insert("tag".into(), "VariantStruct".into());
+        map.insert("a".into(), (123 as INT).into());
+        assert_eq!(
+            MyEnum::VariantStruct { a: 123 },
+            from_dynamic(&map.into()).unwrap()
+        );
+    }
+
+    {
+        let mut map = Map::new();
+        map.insert("tag".into(), "VariantEmptyStruct".into());
+        assert_eq!(
+            MyEnum::VariantEmptyStruct {},
+            from_dynamic(&map.into()).unwrap()
+        );
+    }
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_de_adjacently_tagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Debug, PartialEq, Deserialize)]
+    #[serde(tag = "tag", content = "content", deny_unknown_fields)]
+    enum MyEnum {
+        VariantUnit,
+        #[cfg(not(feature = "no_index"))]
+        VariantUnitTuple(),
+        VariantNewtype(i32),
+        #[cfg(not(feature = "no_index"))]
+        VariantTuple(i32, i32),
+        VariantEmptyStruct {},
+        VariantStruct {
+            a: i32,
+        },
+    }
+
+    {
+        let mut map_outer = Map::new();
+        map_outer.insert("tag".into(), "VariantUnit".into());
+        assert_eq!(
+            MyEnum::VariantUnit,
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let array: Array = vec![];
+        let mut map_outer = Map::new();
+        map_outer.insert("tag".into(), "VariantUnitTuple".into());
+        map_outer.insert("content".into(), array.into());
+        assert_eq!(
+            MyEnum::VariantUnitTuple(),
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    {
+        let mut map_outer = Map::new();
+        map_outer.insert("tag".into(), "VariantNewtype".into());
+        map_outer.insert("content".into(), (123 as INT).into());
+        assert_eq!(
+            MyEnum::VariantNewtype(123),
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    #[cfg(not(feature = "no_index"))]
+    {
+        let array: Array = vec![(123 as INT).into(), (456 as INT).into()];
+        let mut map_outer = Map::new();
+        map_outer.insert("tag".into(), "VariantTuple".into());
+        map_outer.insert("content".into(), array.into());
+        assert_eq!(
+            MyEnum::VariantTuple(123, 456),
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    {
+        let map_inner = Map::new();
+        let mut map_outer = Map::new();
+        map_outer.insert("tag".into(), "VariantEmptyStruct".into());
+        map_outer.insert("content".into(), map_inner.into());
+        assert_eq!(
+            MyEnum::VariantEmptyStruct {},
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    {
+        let mut map_inner = Map::new();
+        map_inner.insert("a".into(), (123 as INT).into());
+        let mut map_outer = Map::new();
+        map_outer.insert("tag".into(), "VariantStruct".into());
+        map_outer.insert("content".into(), map_inner.into());
+        assert_eq!(
+            MyEnum::VariantStruct { a: 123 },
+            from_dynamic(&map_outer.into()).unwrap()
+        );
+    }
+
+    Ok(())
+}
+
+#[test]
+#[cfg(not(feature = "no_object"))]
+fn test_serde_de_untagged_enum() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Debug, PartialEq, Deserialize)]
+    #[serde(untagged, deny_unknown_fields)]
+    enum MyEnum {
+        VariantEmptyStruct {},
+        VariantStruct1 { a: i32 },
+        VariantStruct2 { b: i32 },
+    }
+
+    {
+        let map = Map::new();
+        assert_eq!(
+            MyEnum::VariantEmptyStruct {},
+            from_dynamic(&map.into()).unwrap()
+        );
+    }
+
+    {
+        let mut map = Map::new();
+        map.insert("a".into(), (123 as INT).into());
+        assert_eq!(
+            MyEnum::VariantStruct1 { a: 123 },
+            from_dynamic(&map.into()).unwrap()
+        );
+    }
+
+    {
+        let mut map = Map::new();
+        map.insert("b".into(), (123 as INT).into());
+        assert_eq!(
+            MyEnum::VariantStruct2 { b: 123 },
+            from_dynamic(&map.into()).unwrap()
+        );
+    }
+
+    Ok(())
+}
diff --git a/tests/var_scope.rs b/tests/var_scope.rs
index fde83a05..0b3cc1b9 100644
--- a/tests/var_scope.rs
+++ b/tests/var_scope.rs
@@ -7,7 +7,7 @@ fn test_var_scope() -> Result<(), Box<EvalAltResult>> {
 
     engine.eval_with_scope::<()>(&mut scope, "let x = 4 + 5")?;
     assert_eq!(engine.eval_with_scope::<INT>(&mut scope, "x")?, 9);
-    engine.eval_with_scope::<()>(&mut scope, "x = x + 1; x = x + 2;")?;
+    engine.eval_with_scope::<()>(&mut scope, "x += 1; x += 2;")?;
     assert_eq!(engine.eval_with_scope::<INT>(&mut scope, "x")?, 12);
 
     scope.set_value("x", 42 as INT);
diff --git a/tests/while_loop.rs b/tests/while_loop.rs
index 8916cd7c..bbcd091b 100644
--- a/tests/while_loop.rs
+++ b/tests/while_loop.rs
@@ -10,10 +10,10 @@ fn test_while() -> Result<(), Box<EvalAltResult>> {
                 let x = 0;
 
                 while x < 10 {
-                    x = x + 1;
+                    x += 1;
                     if x > 5 { break; }
                     if x > 3 { continue; }
-                    x = x + 3;
+                    x += 3;
                 }
                 
                 x