diff --git a/src/deprecated.rs b/src/api/deprecated.rs
similarity index 100%
rename from src/deprecated.rs
rename to src/api/deprecated.rs
diff --git a/src/api/mod.rs b/src/api/mod.rs
new file mode 100644
index 00000000..6b560f94
--- /dev/null
+++ b/src/api/mod.rs
@@ -0,0 +1,5 @@
+//! Module defining the public API of the Rhai engine.
+
+pub mod deprecated;
+pub mod public;
+pub mod settings;
diff --git a/src/engine_api.rs b/src/api/public.rs
similarity index 98%
rename from src/engine_api.rs
rename to src/api/public.rs
index 3dc9d82e..f29ea0d6 100644
--- a/src/engine_api.rs
+++ b/src/api/public.rs
@@ -1,14 +1,12 @@
-//! Module that defines the extern API of [`Engine`].
+//! Module that defines the public API of [`Engine`].
 
-use crate::dynamic::Variant;
 use crate::engine::{EvalContext, EvalState, Imports};
-use crate::fn_call::FnCallArgs;
-use crate::fn_native::SendSync;
-use crate::fn_register::RegisterNativeFunction;
-use crate::parse::ParseState;
+use crate::func::{call::FnCallArgs, native::SendSync, register::RegisterNativeFunction};
+use crate::parser::ParseState;
+use crate::types::dynamic::Variant;
 use crate::{
-    scope::Scope, Dynamic, Engine, EvalAltResult, FnAccess, FnNamespace, Identifier, Module,
-    NativeCallContext, ParseError, Position, RhaiResult, Shared, AST,
+    Dynamic, Engine, EvalAltResult, FnAccess, FnNamespace, Identifier, Module, NativeCallContext,
+    ParseError, Position, RhaiResult, Scope, Shared, AST,
 };
 use std::any::{type_name, TypeId};
 #[cfg(feature = "no_std")]
@@ -937,12 +935,12 @@ impl Engine {
             name: impl AsRef<str> + Into<Identifier>,
             module: Shared<Module>,
         ) {
-            let separator = crate::token::Token::DoubleColon.syntax();
+            let separator = crate::tokenizer::Token::DoubleColon.syntax();
 
             if !name.as_ref().contains(separator.as_ref()) {
                 if !module.is_indexed() {
                     // Index the module (making a clone copy if necessary) if it is not indexed
-                    let mut module = crate::fn_native::shared_take_or_clone(module);
+                    let mut module = crate::func::native::shared_take_or_clone(module);
                     module.build_index();
                     root.insert(name.into(), module.into());
                 } else {
@@ -960,7 +958,7 @@ impl Engine {
                     root.insert(sub_module.into(), m.into());
                 } else {
                     let m = root.remove(sub_module).expect("contains sub-module");
-                    let mut m = crate::fn_native::shared_take_or_clone(m);
+                    let mut m = crate::func::native::shared_take_or_clone(m);
                     register_static_module_raw(m.sub_modules_mut(), remainder, module);
                     m.build_index();
                     root.insert(sub_module.into(), m.into());
@@ -1053,7 +1051,7 @@ impl Engine {
     ) -> Result<AST, Box<EvalAltResult>> {
         use crate::{
             ast::{ASTNode, Expr, Stmt},
-            fn_native::shared_take_or_clone,
+            func::native::shared_take_or_clone,
             module::resolvers::StaticModuleResolver,
         };
         use std::collections::BTreeSet;
@@ -1349,7 +1347,7 @@ impl Engine {
         json: impl AsRef<str>,
         has_null: bool,
     ) -> Result<Map, Box<EvalAltResult>> {
-        use crate::token::Token;
+        use crate::tokenizer::Token;
 
         fn parse_json_inner(
             engine: &Engine,
@@ -2026,7 +2024,7 @@ impl Engine {
 
         // Check for data race.
         #[cfg(not(feature = "no_closure"))]
-        crate::fn_call::ensure_no_data_race(name, args, false)?;
+        crate::func::call::ensure_no_data_race(name, args, false)?;
 
         self.call_script_fn(
             scope,
@@ -2084,7 +2082,7 @@ impl Engine {
 
         let statements = std::mem::take(ast.statements_mut());
 
-        crate::optimize::optimize_into_ast(self, scope, statements, lib, optimization_level)
+        crate::optimizer::optimize_into_ast(self, scope, statements, lib, optimization_level)
     }
     /// _(metadata)_ Generate a list of all registered functions.
     /// Exported under the `metadata` feature only.
@@ -2184,14 +2182,14 @@ impl Engine {
     /// > `Fn(token: Token, pos: Position, state: &TokenizeState) -> Token`
     ///
     /// where:
-    /// * [`token`][crate::token::Token]: current token parsed
+    /// * [`token`][crate::tokenizer::Token]: current token parsed
     /// * [`pos`][`Position`]: location of the token
-    /// * [`state`][crate::token::TokenizeState]: current state of the tokenizer
+    /// * [`state`][crate::tokenizer::TokenizeState]: current state of the tokenizer
     ///
     /// ## Raising errors
     ///
     /// It is possible to raise a parsing error by returning
-    /// [`Token::LexError`][crate::token::Token::LexError] as the mapped token.
+    /// [`Token::LexError`][crate::tokenizer::Token::LexError] as the mapped token.
     ///
     /// # Example
     ///
@@ -2225,7 +2223,11 @@ impl Engine {
     #[inline(always)]
     pub fn on_parse_token(
         &mut self,
-        callback: impl Fn(crate::token::Token, Position, &crate::token::TokenizeState) -> crate::token::Token
+        callback: impl Fn(
+                crate::tokenizer::Token,
+                Position,
+                &crate::tokenizer::TokenizeState,
+            ) -> crate::tokenizer::Token
             + SendSync
             + 'static,
     ) -> &mut Self {
diff --git a/src/engine_settings.rs b/src/api/settings.rs
similarity index 99%
rename from src/engine_settings.rs
rename to src/api/settings.rs
index 600434f9..8a5682f3 100644
--- a/src/engine_settings.rs
+++ b/src/api/settings.rs
@@ -1,6 +1,6 @@
 //! Configuration settings for [`Engine`].
 
-use crate::token::Token;
+use crate::tokenizer::Token;
 use crate::Engine;
 use crate::{engine::Precedence, Identifier};
 #[cfg(feature = "no_std")]
diff --git a/src/ast.rs b/src/ast.rs
index 2a19abc1..4a6a81d9 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -1,10 +1,10 @@
 //! Module defining the AST (abstract syntax tree).
 
 use crate::calc_fn_hash;
-use crate::dynamic::Union;
-use crate::fn_native::shared_make_mut;
+use crate::func::native::shared_make_mut;
 use crate::module::NamespaceRef;
-use crate::token::Token;
+use crate::tokenizer::Token;
+use crate::types::dynamic::Union;
 use crate::{
     Dynamic, FnNamespace, Identifier, ImmutableString, Module, Position, Shared, StaticVec, INT,
 };
diff --git a/src/custom_syntax.rs b/src/custom_syntax.rs
index 9de6af3f..a2040dbe 100644
--- a/src/custom_syntax.rs
+++ b/src/custom_syntax.rs
@@ -1,11 +1,11 @@
 //! Module implementing custom syntax for [`Engine`].
 
 use crate::ast::Expr;
-use crate::dynamic::Variant;
 use crate::engine::EvalContext;
-use crate::fn_native::SendSync;
+use crate::func::native::SendSync;
 use crate::r#unsafe::unsafe_try_cast;
-use crate::token::{is_valid_identifier, Token};
+use crate::tokenizer::{is_valid_identifier, Token};
+use crate::types::dynamic::Variant;
 use crate::{
     Engine, Identifier, ImmutableString, LexError, ParseError, Position, RhaiResult, Shared,
     StaticVec, INT,
diff --git a/src/engine.rs b/src/engine.rs
index 99845865..700225df 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -2,16 +2,18 @@
 
 use crate::ast::{Expr, FnCallExpr, Ident, OpAssignment, Stmt, AST_OPTION_FLAGS::*};
 use crate::custom_syntax::CustomSyntax;
-use crate::dynamic::{map_std_type_name, AccessMode, Union, Variant};
-use crate::fn_hash::get_hasher;
-use crate::fn_native::{
-    CallableFunction, IteratorFn, OnDebugCallback, OnParseTokenCallback, OnPrintCallback,
-    OnVarCallback,
+use crate::func::{
+    hashing::get_hasher,
+    native::{
+        CallableFunction, IteratorFn, OnDebugCallback, OnParseTokenCallback, OnPrintCallback,
+        OnVarCallback,
+    },
 };
 use crate::module::NamespaceRef;
 use crate::packages::{Package, StandardPackage};
 use crate::r#unsafe::unsafe_cast_var_name_to_lifetime;
-use crate::token::Token;
+use crate::tokenizer::Token;
+use crate::types::dynamic::{map_std_type_name, AccessMode, Union, Variant};
 use crate::{
     Dynamic, EvalAltResult, Identifier, ImmutableString, Module, Position, RhaiResult, Scope,
     Shared, StaticVec, INT,
@@ -214,7 +216,7 @@ impl Imports {
         &'a mut self,
     ) -> Option<impl DerefMut<Target = BTreeMap<Identifier, Dynamic>> + 'a> {
         if let Some(ref global_constants) = self.global_constants {
-            Some(crate::fn_native::shared_write_lock(global_constants))
+            Some(crate::func::native::shared_write_lock(global_constants))
         } else {
             None
         }
@@ -228,7 +230,7 @@ impl Imports {
             self.global_constants = Some(dict.into());
         }
 
-        crate::fn_native::shared_write_lock(self.global_constants.as_mut().expect("`Some`"))
+        crate::func::native::shared_write_lock(self.global_constants.as_mut().expect("`Some`"))
             .insert(name.into(), value);
     }
     /// Get the pre-calculated index getter hash.
@@ -470,7 +472,12 @@ pub enum Target<'a> {
     /// The target is a mutable reference to a Shared `Dynamic` value.
     /// It holds both the access guard and the original shared value.
     #[cfg(not(feature = "no_closure"))]
-    LockGuard((crate::dynamic::DynamicWriteLock<'a, Dynamic>, Dynamic)),
+    LockGuard(
+        (
+            crate::types::dynamic::DynamicWriteLock<'a, Dynamic>,
+            Dynamic,
+        ),
+    ),
     /// The target is a temporary `Dynamic` value (i.e. the mutation can cause no side effects).
     TempValue(Dynamic),
     /// The target is a bit inside an [`INT`][crate::INT].
@@ -1004,7 +1011,7 @@ pub struct Engine {
     pub(crate) debug: Option<OnDebugCallback>,
     /// Callback closure for progress reporting.
     #[cfg(not(feature = "unchecked"))]
-    pub(crate) progress: Option<crate::fn_native::OnProgressCallback>,
+    pub(crate) progress: Option<crate::func::native::OnProgressCallback>,
 
     /// Optimize the AST after compilation.
     #[cfg(not(feature = "no_optimize"))]
@@ -3081,7 +3088,7 @@ impl Engine {
                     if let Some(name) = export.as_ref().map(|x| x.name.clone()) {
                         if !module.is_indexed() {
                             // Index the module (making a clone copy if necessary) if it is not indexed
-                            let mut module = crate::fn_native::shared_take_or_clone(module);
+                            let mut module = crate::func::native::shared_take_or_clone(module);
                             module.build_index();
                             mods.push(name, module);
                         } else {
@@ -3139,7 +3146,7 @@ impl Engine {
     fn check_return_value(&self, mut result: RhaiResult) -> RhaiResult {
         if let Ok(ref mut r) = result {
             // Concentrate all empty strings into one instance to save memory
-            if let Dynamic(crate::dynamic::Union::Str(s, _, _)) = r {
+            if let Dynamic(crate::types::dynamic::Union::Str(s, _, _)) = r {
                 if s.is_empty() {
                     if !s.ptr_eq(&self.empty_string) {
                         *s = self.const_empty_string();
diff --git a/src/fn_args.rs b/src/func/args.rs
similarity index 98%
rename from src/fn_args.rs
rename to src/func/args.rs
index 3f6f11de..46653724 100644
--- a/src/fn_args.rs
+++ b/src/func/args.rs
@@ -3,7 +3,7 @@
 #![cfg(not(feature = "no_function"))]
 #![allow(non_snake_case)]
 
-use crate::dynamic::Variant;
+use crate::types::dynamic::Variant;
 use crate::Dynamic;
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/fn_builtin.rs b/src/func/builtin.rs
similarity index 99%
rename from src/fn_builtin.rs
rename to src/func/builtin.rs
index d2328b0c..321ad7d7 100644
--- a/src/fn_builtin.rs
+++ b/src/func/builtin.rs
@@ -1,9 +1,8 @@
 //! Built-in implementations for common operators.
 
+use super::call::FnCallArgs;
 use crate::engine::OP_CONTAINS;
-use crate::fn_call::FnCallArgs;
-use crate::fn_native::NativeCallContext;
-use crate::{Dynamic, ImmutableString, RhaiResult, INT};
+use crate::{Dynamic, ImmutableString, NativeCallContext, RhaiResult, INT};
 use std::any::TypeId;
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/fn_call.rs b/src/func/call.rs
similarity index 99%
rename from src/fn_call.rs
rename to src/func/call.rs
index fb3dc56e..ec49af73 100644
--- a/src/fn_call.rs
+++ b/src/func/call.rs
@@ -1,21 +1,19 @@
 //! Implement function-calling mechanism for [`Engine`].
 
+use super::builtin::{get_builtin_binary_op_fn, get_builtin_op_assignment_fn};
+use super::native::{CallableFunction, FnAny};
 use crate::ast::FnCallHashes;
 use crate::engine::{
     EvalState, FnResolutionCacheEntry, Imports, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR,
     KEYWORD_FN_PTR_CALL, KEYWORD_FN_PTR_CURRY, KEYWORD_IS_DEF_VAR, KEYWORD_PRINT, KEYWORD_TYPE_OF,
     MAX_DYNAMIC_PARAMETERS,
 };
-use crate::fn_builtin::{get_builtin_binary_op_fn, get_builtin_op_assignment_fn};
-use crate::fn_native::FnAny;
 use crate::module::NamespaceRef;
-use crate::token::Token;
+use crate::tokenizer::Token;
 use crate::{
     ast::{Expr, Stmt},
-    calc_fn_hash, calc_fn_params_hash, combine_hashes,
-    fn_native::CallableFunction,
-    Dynamic, Engine, EvalAltResult, FnPtr, Identifier, ImmutableString, Module, ParseErrorType,
-    Position, RhaiResult, Scope, StaticVec,
+    calc_fn_hash, calc_fn_params_hash, combine_hashes, Dynamic, Engine, EvalAltResult, FnPtr,
+    Identifier, ImmutableString, Module, ParseErrorType, Position, RhaiResult, Scope, StaticVec,
 };
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/fn_func.rs b/src/func/func.rs
similarity index 99%
rename from src/fn_func.rs
rename to src/func/func.rs
index b33e273f..f442b6fb 100644
--- a/src/fn_func.rs
+++ b/src/func/func.rs
@@ -3,7 +3,7 @@
 #![cfg(not(feature = "no_function"))]
 #![allow(non_snake_case)]
 
-use crate::dynamic::Variant;
+use crate::types::dynamic::Variant;
 use crate::{Engine, EvalAltResult, ParseError, Scope, SmartString, AST};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/fn_hash.rs b/src/func/hashing.rs
similarity index 100%
rename from src/fn_hash.rs
rename to src/func/hashing.rs
diff --git a/src/func/mod.rs b/src/func/mod.rs
new file mode 100644
index 00000000..59e83937
--- /dev/null
+++ b/src/func/mod.rs
@@ -0,0 +1,10 @@
+//! Module defining mechanisms to handle function calls in Rhai.
+
+pub mod args;
+pub mod builtin;
+pub mod call;
+pub mod func;
+pub mod hashing;
+pub mod native;
+pub mod plugin;
+pub mod register;
diff --git a/src/fn_native.rs b/src/func/native.rs
similarity index 99%
rename from src/fn_native.rs
rename to src/func/native.rs
index 7225e5c9..cf8064c7 100644
--- a/src/fn_native.rs
+++ b/src/func/native.rs
@@ -1,10 +1,10 @@
 //! Module defining interfaces to native-Rust functions.
 
+use super::call::FnCallArgs;
 use crate::ast::{FnAccess, FnCallHashes};
 use crate::engine::{EvalState, Imports};
-use crate::fn_call::FnCallArgs;
 use crate::plugin::PluginFunction;
-use crate::token::{Token, TokenizeState};
+use crate::tokenizer::{Token, TokenizeState};
 use crate::{
     calc_fn_hash, Dynamic, Engine, EvalAltResult, EvalContext, Module, Position, RhaiResult,
 };
diff --git a/src/plugin.rs b/src/func/plugin.rs
similarity index 92%
rename from src/plugin.rs
rename to src/func/plugin.rs
index 779f3fd7..b508c52d 100644
--- a/src/plugin.rs
+++ b/src/func/plugin.rs
@@ -1,7 +1,7 @@
 //! Module defining macros for developing _plugins_.
 
-use crate::fn_call::FnCallArgs;
-pub use crate::fn_native::CallableFunction;
+use super::call::FnCallArgs;
+pub use super::native::CallableFunction;
 pub use crate::{
     Dynamic, Engine, EvalAltResult, FnAccess, FnNamespace, ImmutableString, Module,
     NativeCallContext, Position,
diff --git a/src/fn_register.rs b/src/func/register.rs
similarity index 98%
rename from src/fn_register.rs
rename to src/func/register.rs
index 8fab0805..e317f51b 100644
--- a/src/fn_register.rs
+++ b/src/func/register.rs
@@ -2,11 +2,11 @@
 
 #![allow(non_snake_case)]
 
-use crate::dynamic::{DynamicWriteLock, Variant};
-use crate::fn_call::FnCallArgs;
-use crate::fn_native::{CallableFunction, FnAny, SendSync};
+use crate::func::call::FnCallArgs;
+use crate::func::native::{CallableFunction, FnAny, SendSync};
 use crate::r#unsafe::unsafe_try_cast;
-use crate::token::Position;
+use crate::tokenizer::Position;
+use crate::types::dynamic::{DynamicWriteLock, Variant};
 use crate::{Dynamic, EvalAltResult, NativeCallContext};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/lib.rs b/src/lib.rs
index 96c1391e..861bee3f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -69,33 +69,19 @@ use std::prelude::v1::*;
 
 // Internal modules
 
+mod api;
 mod ast;
 mod custom_syntax;
-mod deprecated;
-mod dynamic;
 mod engine;
-mod engine_api;
-mod engine_settings;
-mod error;
-mod error_parsing;
-mod fn_args;
-mod fn_builtin;
-mod fn_call;
-mod fn_func;
-mod fn_hash;
-mod fn_native;
-mod fn_ptr;
-mod fn_register;
-mod immutable_string;
+mod func;
 mod module;
 #[cfg(not(feature = "no_optimize"))]
-mod optimize;
+mod optimizer;
 pub mod packages;
-mod parse;
-pub mod plugin;
-mod scope;
+mod parser;
 mod tests;
-mod token;
+mod tokenizer;
+mod types;
 mod r#unsafe;
 
 type RhaiResult = Result<Dynamic, Box<EvalAltResult>>;
@@ -132,17 +118,18 @@ pub type FLOAT = f32;
 
 pub use ast::{FnAccess, AST};
 pub use custom_syntax::Expression;
-pub use dynamic::Dynamic;
 pub use engine::{Engine, EvalContext, OP_CONTAINS, OP_EQUALS};
-pub use error::EvalAltResult;
-pub use error_parsing::{LexError, ParseError, ParseErrorType};
-pub use fn_native::NativeCallContext;
-pub use fn_ptr::FnPtr;
-pub use fn_register::RegisterNativeFunction;
-pub use immutable_string::ImmutableString;
+pub use func::{native::NativeCallContext, register::RegisterNativeFunction};
 pub use module::{FnNamespace, Module};
-pub use scope::Scope;
-pub use token::Position;
+pub use tokenizer::Position;
+pub use types::{
+    dynamic::Dynamic,
+    error::EvalAltResult,
+    fn_ptr::FnPtr,
+    immutable_string::ImmutableString,
+    parse_error::{LexError, ParseError, ParseErrorType},
+    scope::Scope,
+};
 
 /// An identifier in Rhai. [`SmartString`](https://crates.io/crates/smartstring) is used because most
 /// identifiers are ASCII and short, fewer than 23 characters, so they can be stored inline.
@@ -169,23 +156,22 @@ pub type Identifier = SmartString;
 pub type Identifier = ImmutableString;
 
 /// Alias to [`Rc`][std::rc::Rc] or [`Arc`][std::sync::Arc] depending on the `sync` feature flag.
-pub use fn_native::Shared;
+pub use func::native::Shared;
 
-//// Alias to [`RefCell`][std::cell::RefCell] or [`RwLock`][std::sync::RwLock] depending on the `sync` feature flag.
-pub use fn_native::Locked;
+/// Alias to [`RefCell`][std::cell::RefCell] or [`RwLock`][std::sync::RwLock] depending on the `sync` feature flag.
+pub use func::native::Locked;
 
-pub(crate) use fn_hash::{
+pub(crate) use func::hashing::{
     calc_fn_hash, calc_fn_params_hash, calc_qualified_fn_hash, calc_qualified_var_hash,
     combine_hashes,
 };
 
 pub use rhai_codegen::*;
 
-#[cfg(not(feature = "no_function"))]
-pub use fn_func::Func;
+pub use func::plugin;
 
 #[cfg(not(feature = "no_function"))]
-pub use fn_args::FuncArgs;
+pub use func::{args::FuncArgs, func::Func};
 
 #[cfg(not(feature = "no_function"))]
 pub use ast::ScriptFnMetadata;
@@ -211,28 +197,28 @@ pub use module::resolvers as module_resolvers;
 pub mod serde;
 
 #[cfg(not(feature = "no_optimize"))]
-pub use optimize::OptimizationLevel;
+pub use optimizer::OptimizationLevel;
+
+// Expose internal data structures.
 
 #[cfg(feature = "internals")]
 #[deprecated = "this type is volatile and may change"]
-pub use dynamic::{AccessMode, DynamicReadLock, DynamicWriteLock, Variant};
+pub use types::dynamic::{AccessMode, DynamicReadLock, DynamicWriteLock, Variant};
 
-// Expose internal data structures.
 #[cfg(feature = "internals")]
 #[deprecated = "this function is volatile and may change"]
-pub use token::{get_next_token, parse_string_literal};
+pub use tokenizer::{get_next_token, parse_string_literal};
 
-// Expose internal data structures.
 #[cfg(feature = "internals")]
 #[deprecated = "this type is volatile and may change"]
-pub use token::{
+pub use tokenizer::{
     InputStream, MultiInputsStream, Token, TokenIterator, TokenizeState, TokenizerControl,
     TokenizerControlBlock,
 };
 
 #[cfg(feature = "internals")]
 #[deprecated = "this type is volatile and may change"]
-pub use parse::{IdentifierBuilder, ParseState};
+pub use parser::{IdentifierBuilder, ParseState};
 
 #[cfg(feature = "internals")]
 #[deprecated = "this type is volatile and may change"]
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 78ffba6b..6d5f3975 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -1,12 +1,14 @@
 //! Module defining external-loaded modules for Rhai.
 
 use crate::ast::{FnAccess, Ident};
-use crate::dynamic::Variant;
-use crate::fn_call::FnCallArgs;
-use crate::fn_native::{shared_take_or_clone, CallableFunction, IteratorFn, SendSync};
-use crate::fn_register::RegisterNativeFunction;
-use crate::parse::IdentifierBuilder;
-use crate::token::Token;
+use crate::func::{
+    call::FnCallArgs,
+    native::{shared_take_or_clone, CallableFunction, IteratorFn, SendSync},
+    register::RegisterNativeFunction,
+};
+use crate::parser::IdentifierBuilder;
+use crate::tokenizer::Token;
+use crate::types::dynamic::Variant;
 use crate::{
     calc_fn_params_hash, calc_qualified_fn_hash, combine_hashes, Dynamic, EvalAltResult,
     Identifier, ImmutableString, NativeCallContext, Shared, StaticVec,
diff --git a/src/module/resolvers/file.rs b/src/module/resolvers/file.rs
index 1cf096f8..7af23527 100644
--- a/src/module/resolvers/file.rs
+++ b/src/module/resolvers/file.rs
@@ -1,4 +1,4 @@
-use crate::fn_native::shared_write_lock;
+use crate::func::native::shared_write_lock;
 use crate::{Engine, EvalAltResult, Identifier, Module, ModuleResolver, Position, Scope, Shared};
 
 #[cfg(feature = "no_std")]
diff --git a/src/module/resolvers/mod.rs b/src/module/resolvers/mod.rs
index 13030ad7..17f48f99 100644
--- a/src/module/resolvers/mod.rs
+++ b/src/module/resolvers/mod.rs
@@ -1,4 +1,4 @@
-use crate::fn_native::SendSync;
+use crate::func::native::SendSync;
 use crate::{Engine, EvalAltResult, Module, Position, Shared, AST};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/optimize.rs b/src/optimizer.rs
similarity index 99%
rename from src/optimize.rs
rename to src/optimizer.rs
index 3afd75d5..dc2ed085 100644
--- a/src/optimize.rs
+++ b/src/optimizer.rs
@@ -1,13 +1,13 @@
 //! Module implementing the [`AST`] optimizer.
 
 use crate::ast::{Expr, OpAssignment, Stmt, AST_OPTION_FLAGS::*};
-use crate::dynamic::AccessMode;
 use crate::engine::{
     EvalState, Imports, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF,
 };
-use crate::fn_builtin::get_builtin_binary_op_fn;
-use crate::fn_hash::get_hasher;
-use crate::token::Token;
+use crate::func::builtin::get_builtin_binary_op_fn;
+use crate::func::hashing::get_hasher;
+use crate::tokenizer::Token;
+use crate::types::dynamic::AccessMode;
 use crate::{
     calc_fn_hash, calc_fn_params_hash, combine_hashes, Dynamic, Engine, FnPtr, ImmutableString,
     Module, Position, Scope, StaticVec, AST,
@@ -1157,7 +1157,7 @@ pub fn optimize_into_ast(
             _functions
                 .into_iter()
                 .map(|fn_def| {
-                    let mut fn_def = crate::fn_native::shared_take_or_clone(fn_def);
+                    let mut fn_def = crate::func::native::shared_take_or_clone(fn_def);
 
                     // Optimize the function body
                     let body = mem::take(fn_def.body.deref_mut());
diff --git a/src/packages/fn_basic.rs b/src/packages/fn_basic.rs
index ab154217..5ec75874 100644
--- a/src/packages/fn_basic.rs
+++ b/src/packages/fn_basic.rs
@@ -112,7 +112,7 @@ fn collect_fn_metadata(ctx: NativeCallContext) -> crate::Array {
                 let ns = format!(
                     "{}{}{}",
                     namespace,
-                    crate::token::Token::DoubleColon.literal_syntax(),
+                    crate::tokenizer::Token::DoubleColon.literal_syntax(),
                     ns
                 );
                 scan_module(list, dict, ns.into(), m.as_ref())
diff --git a/src/packages/iter_basic.rs b/src/packages/iter_basic.rs
index 16d3d5e4..6f334973 100644
--- a/src/packages/iter_basic.rs
+++ b/src/packages/iter_basic.rs
@@ -1,4 +1,4 @@
-use crate::dynamic::Variant;
+use crate::types::dynamic::Variant;
 use crate::{def_package, EvalAltResult, INT};
 use std::iter::{ExactSizeIterator, FusedIterator};
 use std::ops::Range;
diff --git a/src/packages/lang_core.rs b/src/packages/lang_core.rs
index 91c78dba..cab9ebc3 100644
--- a/src/packages/lang_core.rs
+++ b/src/packages/lang_core.rs
@@ -1,6 +1,6 @@
 use crate::def_package;
-use crate::dynamic::Tag;
 use crate::plugin::*;
+use crate::types::dynamic::Tag;
 use crate::{Dynamic, EvalAltResult, INT};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/packages/math_basic.rs b/src/packages/math_basic.rs
index b97fb9db..1e65f66f 100644
--- a/src/packages/math_basic.rs
+++ b/src/packages/math_basic.rs
@@ -6,10 +6,7 @@ use crate::{def_package, Position, INT};
 use std::prelude::v1::*;
 
 #[cfg(not(feature = "no_float"))]
-use crate::FLOAT;
-
-#[cfg(not(feature = "no_float"))]
-use crate::error::EvalAltResult;
+use crate::{EvalAltResult, FLOAT};
 
 #[cfg(feature = "no_std")]
 #[cfg(not(feature = "no_float"))]
diff --git a/src/parse.rs b/src/parser.rs
similarity index 99%
rename from src/parse.rs
rename to src/parser.rs
index 7258f2f3..6cfa647b 100644
--- a/src/parse.rs
+++ b/src/parser.rs
@@ -5,14 +5,14 @@ use crate::ast::{
     StmtBlock, AST_OPTION_FLAGS::*,
 };
 use crate::custom_syntax::{markers::*, CustomSyntax};
-use crate::dynamic::AccessMode;
 use crate::engine::{Precedence, KEYWORD_THIS, OP_CONTAINS};
-use crate::fn_hash::get_hasher;
+use crate::func::hashing::get_hasher;
 use crate::module::NamespaceRef;
-use crate::token::{
+use crate::tokenizer::{
     is_keyword_function, is_valid_function_name, is_valid_identifier, Token, TokenStream,
     TokenizerControl,
 };
+use crate::types::dynamic::AccessMode;
 use crate::{
     calc_fn_hash, calc_qualified_fn_hash, calc_qualified_var_hash, Engine, Identifier,
     ImmutableString, LexError, ParseError, ParseErrorType, Position, Scope, Shared, StaticVec, AST,
@@ -2745,7 +2745,7 @@ fn parse_stmt(
                 comments_pos = *pos;
             }
 
-            if !crate::token::is_doc_comment(comment) {
+            if !crate::tokenizer::is_doc_comment(comment) {
                 unreachable!("expecting doc-comment, but gets {:?}", comment);
             }
 
@@ -3278,7 +3278,7 @@ impl Engine {
         statements.push(Stmt::Expr(expr));
 
         #[cfg(not(feature = "no_optimize"))]
-        return Ok(crate::optimize::optimize_into_ast(
+        return Ok(crate::optimizer::optimize_into_ast(
             self,
             _scope,
             statements,
@@ -3363,7 +3363,7 @@ impl Engine {
         let (statements, _lib) = self.parse_global_level(input, state)?;
 
         #[cfg(not(feature = "no_optimize"))]
-        return Ok(crate::optimize::optimize_into_ast(
+        return Ok(crate::optimizer::optimize_into_ast(
             self,
             _scope,
             statements,
diff --git a/src/serde/de.rs b/src/serde/de.rs
index fc255f02..8c7420e2 100644
--- a/src/serde/de.rs
+++ b/src/serde/de.rs
@@ -1,7 +1,7 @@
 //! Implement deserialization support of [`Dynamic`][crate::Dynamic] for [`serde`].
 
 use super::str::StringSliceDeserializer;
-use crate::dynamic::Union;
+use crate::types::dynamic::Union;
 use crate::{Dynamic, EvalAltResult, ImmutableString, LexError, Position};
 use serde::de::{DeserializeSeed, Error, IntoDeserializer, MapAccess, SeqAccess, Visitor};
 use serde::{Deserialize, Deserializer};
diff --git a/src/serde/serialize.rs b/src/serde/serialize.rs
index 560d489d..d2bd511e 100644
--- a/src/serde/serialize.rs
+++ b/src/serde/serialize.rs
@@ -1,6 +1,6 @@
 //! Implementations of [`serde::Serialize`].
 
-use crate::dynamic::Union;
+use crate::types::dynamic::Union;
 use crate::{Dynamic, ImmutableString};
 use serde::ser::{Serialize, Serializer};
 #[cfg(feature = "no_std")]
@@ -10,7 +10,7 @@ use std::prelude::v1::*;
 use serde::ser::SerializeMap;
 
 #[cfg(not(feature = "no_std"))]
-use crate::dynamic::Variant;
+use crate::types::dynamic::Variant;
 
 impl Serialize for Dynamic {
     fn serialize<S: Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> {
diff --git a/src/token.rs b/src/tokenizer.rs
similarity index 99%
rename from src/token.rs
rename to src/tokenizer.rs
index 13144243..abc6f34f 100644
--- a/src/token.rs
+++ b/src/tokenizer.rs
@@ -4,7 +4,7 @@ use crate::engine::{
     Precedence, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_FN_PTR_CALL,
     KEYWORD_FN_PTR_CURRY, KEYWORD_IS_DEF_VAR, KEYWORD_PRINT, KEYWORD_THIS, KEYWORD_TYPE_OF,
 };
-use crate::fn_native::OnParseTokenCallback;
+use crate::func::native::OnParseTokenCallback;
 use crate::{Engine, LexError, StaticVec, INT};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/dynamic.rs b/src/types/dynamic.rs
similarity index 99%
rename from src/dynamic.rs
rename to src/types/dynamic.rs
index ae530593..f401e104 100644
--- a/src/dynamic.rs
+++ b/src/types/dynamic.rs
@@ -1,6 +1,6 @@
 //! Helper module which defines the [`Any`] trait to to allow dynamic value handling.
 
-use crate::fn_native::SendSync;
+use crate::func::native::SendSync;
 use crate::r#unsafe::{unsafe_cast_box, unsafe_try_cast};
 use crate::{FnPtr, ImmutableString, INT};
 #[cfg(feature = "no_std")]
@@ -38,7 +38,7 @@ use instant::Instant;
 const CHECKED: &str = "data type was checked";
 
 mod private {
-    use crate::fn_native::SendSync;
+    use crate::func::native::SendSync;
     use std::any::Any;
 
     /// A sealed trait that prevents other crates from implementing [`Variant`].
@@ -287,7 +287,7 @@ enum DynamicWriteLockInner<'d, T: Clone> {
     ///
     /// Not available under `no_closure`.
     #[cfg(not(feature = "no_closure"))]
-    Guard(crate::fn_native::LockGuard<'d, Dynamic>),
+    Guard(crate::func::native::LockGuard<'d, Dynamic>),
 }
 
 impl<'d, T: Any + Clone> Deref for DynamicWriteLock<'d, T> {
@@ -1472,7 +1472,7 @@ impl Dynamic {
     pub fn flatten(self) -> Self {
         match self.0 {
             #[cfg(not(feature = "no_closure"))]
-            Union::Shared(cell, _, _) => crate::fn_native::shared_try_take(cell).map_or_else(
+            Union::Shared(cell, _, _) => crate::func::native::shared_try_take(cell).map_or_else(
                 #[cfg(not(feature = "sync"))]
                 |cell| cell.borrow().clone(),
                 #[cfg(feature = "sync")]
@@ -1497,7 +1497,7 @@ impl Dynamic {
             #[cfg(not(feature = "no_closure"))]
             Union::Shared(_, _, _) => match std::mem::take(self).0 {
                 Union::Shared(cell, _, _) => {
-                    *self = crate::fn_native::shared_try_take(cell).map_or_else(
+                    *self = crate::func::native::shared_try_take(cell).map_or_else(
                         #[cfg(not(feature = "sync"))]
                         |cell| cell.borrow().clone(),
                         #[cfg(feature = "sync")]
@@ -1590,7 +1590,7 @@ impl Dynamic {
         match self.0 {
             #[cfg(not(feature = "no_closure"))]
             Union::Shared(ref cell, _, _) => {
-                let value = crate::fn_native::shared_write_lock(cell);
+                let value = crate::func::native::shared_write_lock(cell);
 
                 if (*value).type_id() != TypeId::of::<T>()
                     && TypeId::of::<Dynamic>() != TypeId::of::<T>()
diff --git a/src/error.rs b/src/types/error.rs
similarity index 100%
rename from src/error.rs
rename to src/types/error.rs
diff --git a/src/fn_ptr.rs b/src/types/fn_ptr.rs
similarity index 99%
rename from src/fn_ptr.rs
rename to src/types/fn_ptr.rs
index 47197920..7e2de87c 100644
--- a/src/fn_ptr.rs
+++ b/src/types/fn_ptr.rs
@@ -1,6 +1,6 @@
 //! The `FnPtr` type.
 
-use crate::token::is_valid_identifier;
+use crate::tokenizer::is_valid_identifier;
 use crate::{
     Dynamic, EvalAltResult, Identifier, NativeCallContext, Position, RhaiResult, StaticVec,
 };
diff --git a/src/immutable_string.rs b/src/types/immutable_string.rs
similarity index 99%
rename from src/immutable_string.rs
rename to src/types/immutable_string.rs
index 83bede60..5b446eb0 100644
--- a/src/immutable_string.rs
+++ b/src/types/immutable_string.rs
@@ -1,6 +1,6 @@
 //! The `ImmutableString` type.
 
-use crate::fn_native::{shared_make_mut, shared_take};
+use crate::func::native::{shared_make_mut, shared_take};
 use crate::{Shared, SmartString};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
diff --git a/src/types/mod.rs b/src/types/mod.rs
new file mode 100644
index 00000000..ee2ff553
--- /dev/null
+++ b/src/types/mod.rs
@@ -0,0 +1,8 @@
+//! Module defining Rhai data types.
+
+pub mod dynamic;
+pub mod error;
+pub mod fn_ptr;
+pub mod immutable_string;
+pub mod parse_error;
+pub mod scope;
diff --git a/src/error_parsing.rs b/src/types/parse_error.rs
similarity index 100%
rename from src/error_parsing.rs
rename to src/types/parse_error.rs
diff --git a/src/scope.rs b/src/types/scope.rs
similarity index 99%
rename from src/scope.rs
rename to src/types/scope.rs
index 408922fa..e5fdd8fe 100644
--- a/src/scope.rs
+++ b/src/types/scope.rs
@@ -1,6 +1,6 @@
 //! Module that defines the [`Scope`] type representing a function call-stack scope.
 
-use crate::dynamic::{AccessMode, Variant};
+use super::dynamic::{AccessMode, Variant};
 use crate::{Dynamic, Identifier, StaticVec};
 use std::iter::FromIterator;
 #[cfg(feature = "no_std")]