diff --git a/examples/build.rs b/examples/build.rs
new file mode 100644
index 0000000..d836a61
--- /dev/null
+++ b/examples/build.rs
@@ -0,0 +1,22 @@
+extern crate parity_wasm;
+
+use std::env;
+
+use parity_wasm::builder;
+use parity_wasm::elements;
+
+fn main() {
+    let args = env::args().collect::<Vec<_>>();
+    if args.len() != 2 {
+        println!("Usage: {} output_file.wasm", args[0]);
+        return;
+    }
+
+    let module = builder::module()
+        .functions()
+            .signature().param(elements::ValueType::I32).build()
+            .bind()
+        .build();
+
+    parity_wasm::serialize_to_file(&args[1], module).unwrap();
+}
\ No newline at end of file
diff --git a/src/builder/code.rs b/src/builder/code.rs
index a2dd102..053869a 100644
--- a/src/builder/code.rs
+++ b/src/builder/code.rs
@@ -8,49 +8,25 @@ pub enum Signature {
 
 pub struct SignatureBuilder<F=Identity> {
     callback: F,
-    signature: Signature,
+    signature: elements::FunctionType,
 }
 
-impl<F> SignatureBuilder<F> where F: Invoke<Signature> {
+impl<F> SignatureBuilder<F> where F: Invoke<elements::FunctionType> {
     pub fn with_callback(callback: F) -> Self {
         SignatureBuilder { 
             callback: callback, 
-            signature: Signature::TypeReference(0) 
+            signature: elements::FunctionType::default(),
         }
     }
 
-    pub fn type_ref(mut self, val: u32) -> Self {
-        self.signature = Signature::TypeReference(val);
-        self
-    }
-
     pub fn param(mut self, value_type: elements::ValueType) -> Self {
-        {
-            let signature = &mut self.signature;
-            if let Signature::TypeReference(_) = *signature { 
-                *signature = Signature::Inline(elements::FunctionType::default())
-            }
-
-            if let Signature::Inline(ref mut func_type) = *signature {
-                func_type.params_mut().push(value_type);
-            }
-        }
+        self.signature.params_mut().push(value_type);
 
         self
     }
 
     pub fn return_type(mut self, value_type: elements::ValueType) -> Self {
-        {
-            let signature = &mut self.signature;
-            if let Signature::TypeReference(_) = *signature { 
-                *signature = Signature::Inline(elements::FunctionType::default())
-            }
-
-            if let Signature::Inline(ref mut func_type) = *signature {
-                *func_type.return_type_mut() = Some(value_type);
-            }
-        }
-                
+        *self.signature.return_type_mut() = Some(value_type);                
         self
     }
 
@@ -59,6 +35,27 @@ impl<F> SignatureBuilder<F> where F: Invoke<Signature> {
     }
 }
 
+pub struct TypeRefBuilder<F=Identity> {
+    callback: F,
+    type_ref: u32,
+}
+
+impl<F> TypeRefBuilder<F> where F: Invoke<u32> {
+    pub fn with_callback(callback: F) -> Self {
+        TypeRefBuilder { 
+            callback: callback, 
+            type_ref: 0
+        }
+    }
+
+    pub fn val(mut self, val: u32) -> Self {
+        self.type_ref = val;
+        self
+    }
+
+    pub fn build(self) -> F::Result { self.callback.invoke(self.type_ref) }
+}
+
 pub struct FunctionsBuilder<F=Identity> {
     callback: F,
     section: Vec<Signature>,
@@ -84,16 +81,30 @@ impl<F> FunctionsBuilder<F> {
         self
     }
 
+    pub fn type_ref(self) -> TypeRefBuilder<Self> {
+        TypeRefBuilder::with_callback(self)
+    }    
+}
+
+impl<F> FunctionsBuilder<F> where F: Invoke<SignatureBindings> {
     pub fn signature(self) -> SignatureBuilder<Self> {
         SignatureBuilder::with_callback(self)
     }
 }
 
-impl<F> Invoke<Signature> for FunctionsBuilder<F> {
+impl<F> Invoke<elements::FunctionType> for FunctionsBuilder<F> {
 	type Result = Self;
 
-	fn invoke(self, signature: Signature) -> Self {
-		self.with_signature(signature)
+	fn invoke(self, signature: elements::FunctionType) -> Self {
+		self.with_signature(Signature::Inline(signature))
+    }    
+}
+
+impl<F> Invoke<u32> for FunctionsBuilder<F> {
+	type Result = Self;
+
+	fn invoke(self, type_ref: u32) -> Self {
+		self.with_signature(Signature::TypeReference(type_ref))
     }    
 }
 
@@ -119,21 +130,30 @@ impl<F> FunctionsBuilder<F> where F: Invoke<SignatureBindings> {
     }
 }
 
+/// New function builder.
+pub fn function() -> FunctionsBuilder {
+    FunctionsBuilder::new()
+}
+
 #[cfg(test)]
 mod tests {
 
-    use super::FunctionsBuilder;
+    use super::function;
 
     #[test]
     fn example() {
-        let result = FunctionsBuilder::new()
-            .signature().type_ref(1).build()
+        let result = function()
+            .type_ref().val(1).build()
             .build();
 
         assert_eq!(result.entries().len(), 1);
 
-        let result = FunctionsBuilder::new()
-            .signature().type_ref(1).build()
+        let result = function()
+            .signature()
+                .param(::elements::ValueType::I32)
+                .param(::elements::ValueType::I32)
+                .return_type(::elements::ValueType::I64)
+                .build()
             .bind();      
 
         assert_eq!(result.len(), 1);              
diff --git a/src/builder/mod.rs b/src/builder/mod.rs
index f41fd90..7254828 100644
--- a/src/builder/mod.rs
+++ b/src/builder/mod.rs
@@ -4,4 +4,5 @@ mod invoke;
 mod module;
 mod code;
 
-pub use self::module::{module, ModuleBuilder};
\ No newline at end of file
+pub use self::module::{module, ModuleBuilder};
+pub use self::code::function;
\ No newline at end of file
diff --git a/src/builder/module.rs b/src/builder/module.rs
index 1cec56b..898b4c4 100644
--- a/src/builder/module.rs
+++ b/src/builder/module.rs
@@ -1,11 +1,57 @@
 use super::invoke::{Invoke, Identity};
-use super::code::FunctionsBuilder;
+use super::code::{self, FunctionsBuilder};
 use elements;
 
 /// Module builder
 pub struct ModuleBuilder<F=Identity> {
     callback: F,
-    sections: Vec<elements::Section>,
+    module: ModuleScaffold,
+}
+
+#[derive(Default)]
+struct ModuleScaffold {
+    pub functions: elements::FunctionsSection,
+    pub types: elements::TypeSection,
+    pub other: Vec<elements::Section>,
+}
+
+impl From<elements::Module> for ModuleScaffold {
+    fn from(module: elements::Module) -> Self {
+        let mut funcs: Option<elements::FunctionsSection> = None;
+        let mut types: Option<elements::TypeSection> = None;
+
+        let mut sections = module.into_sections();
+        while let Some(section) = sections.pop() {
+            match section {
+                elements::Section::Type(sect) => { types = Some(sect); }
+                elements::Section::Function(sect) => { funcs = Some(sect); }
+                _ => {}
+            }
+        }
+
+        ModuleScaffold {
+            functions: funcs.unwrap_or_default(),
+            types: types.unwrap_or_default(),
+            other: sections,
+        }
+    }
+}
+
+impl From<ModuleScaffold> for elements::Module {
+    fn from(module: ModuleScaffold) -> Self {
+        let mut sections = Vec::new();
+
+        let types = module.types;
+        if types.types().len() > 0 {
+            sections.push(elements::Section::Type(types));
+        }
+        let functions = module.functions;
+        if functions.entries().len() > 0 {
+            sections.push(elements::Section::Function(functions));
+        }        
+        sections.extend(module.other);
+        elements::Module::new(sections)
+    }
 }
 
 impl ModuleBuilder {
@@ -20,7 +66,7 @@ impl<F> ModuleBuilder<F> where F: Invoke<elements::Module> {
     pub fn with_callback(callback: F) -> Self {
         ModuleBuilder {
             callback: callback,
-            sections: Vec::new(),
+            module: Default::default(),
         }
     }
 
@@ -28,22 +74,51 @@ impl<F> ModuleBuilder<F> where F: Invoke<elements::Module> {
     pub fn with_sections<I>(mut self, sections: I) -> Self 
         where I: IntoIterator<Item=elements::Section>
     {
-        self.sections.extend(sections);
+        self.module.other.extend(sections);
         self
     }
 
+    /// Add additional section
     pub fn with_section(mut self, section: elements::Section) -> Self {
-        self.sections.push(section);
+        self.module.other.push(section);
         self
     }
 
+    /// Binds to the type section, creates additional types when required
+    pub fn with_signatures(mut self, bindings: code::SignatureBindings) -> Self {
+        // todo bind to type section
+
+        {
+            let module = &mut self.module;
+
+            let raw_functions: Vec<u32> = bindings.into_iter().map(|binding|
+                match binding {
+                    code::Signature::Inline(func_type) => {
+                        module.types.types_mut().push(elements::Type::Function(func_type));
+                        module.types.types().len() as u32 - 1
+                    }
+                    code::Signature::TypeReference(type_ref) => {
+                        type_ref
+                    }
+                }
+            ).collect();
+
+            for function in raw_functions {
+                module.functions.entries_mut().push(elements::Func::new(function));
+            }
+        }
+
+        self
+    }
+
+    /// Define functions section
     pub fn functions(self) -> FunctionsBuilder<Self> {
         FunctionsBuilder::with_callback(self)
     }
 
     /// Build module (final step)
     pub fn build(self) -> F::Result {
-        self.callback.invoke(elements::Module::new(self.sections))
+        self.callback.invoke(self.module.into())
     }
 }
 
@@ -57,6 +132,16 @@ impl<F> Invoke<elements::FunctionsSection> for ModuleBuilder<F>
     }    
 }
 
+impl<F> Invoke<code::SignatureBindings> for ModuleBuilder<F>
+    where F: Invoke<elements::Module> 
+{
+    type Result = Self;
+
+    fn invoke(self, bindings: code::SignatureBindings) -> Self {
+        self.with_signatures(bindings)
+    }
+}
+
 /// Start new module builder
 pub fn module() -> ModuleBuilder {
     ModuleBuilder::new()
@@ -73,4 +158,16 @@ mod tests {
         assert_eq!(module.sections().len(), 0);
     }
 
+    #[test]
+    fn functions() {
+        let module = module()
+            .functions()
+                .signature().param(::elements::ValueType::I32).build()
+                .bind()
+            .build();
+
+        assert_eq!(module.type_section().expect("type section to exist").types().len(), 1);
+        assert_eq!(module.functions_section().expect("function section to exist").entries().len(), 1);
+    }
+
 }
diff --git a/src/elements/mod.rs b/src/elements/mod.rs
index 77a3f8c..f003623 100644
--- a/src/elements/mod.rs
+++ b/src/elements/mod.rs
@@ -16,7 +16,7 @@ mod segment;
 pub use self::module::Module;
 pub use self::section::{
     Section, FunctionsSection, CodeSection, MemorySection, DataSection,
-    ImportSection, ExportSection, GlobalSection,
+    ImportSection, ExportSection, GlobalSection, TypeSection,
 };
 pub use self::import_entry::{ImportEntry, MemoryType, TableType, GlobalType, External};
 pub use self::export_entry::{ExportEntry, Internal};
@@ -25,7 +25,7 @@ pub use self::primitives::{
     VarUint32, VarUint7, VarUint1, VarInt7, Uint32, 
     Uint64, VarUint64, CountedList, CountedWriter, CountedListWriter,
 };
-pub use self::types::{ValueType, BlockType, FunctionType};
+pub use self::types::{Type, ValueType, BlockType, FunctionType};
 pub use self::ops::{Opcode, Opcodes, InitExpr};
 pub use self::func::{Func, FuncBody, Local};
 pub use self::segment::{ElementSegment, DataSegment};
@@ -121,4 +121,11 @@ pub fn serialize<T: Serialize>(val: T) -> Result<Vec<u8>, T::Error> {
     let mut buf = Vec::new();
     val.serialize(&mut buf)?;
     Ok(buf)
+}
+
+/// Serialize module to the file
+pub fn serialize_to_file<P: AsRef<::std::path::Path>>(p: P, module: Module) -> Result<(), Error> 
+{ 
+    let mut io = ::std::fs::File::create(p)?;
+    module.serialize(&mut io)
 }
\ No newline at end of file
diff --git a/src/elements/module.rs b/src/elements/module.rs
index ecbcd28..2b37c0f 100644
--- a/src/elements/module.rs
+++ b/src/elements/module.rs
@@ -1,6 +1,6 @@
 use std::io;
 use super::{Deserialize, Serialize, Error, Uint32};
-use super::section::{Section, CodeSection, TypeSection, ImportSection};
+use super::section::{Section, CodeSection, TypeSection, ImportSection, FunctionsSection};
 
 /// WebAssembly module
 pub struct Module {
@@ -9,16 +9,29 @@ pub struct Module {
     sections: Vec<Section>,
 }
 
+impl Default for Module {
+    fn default() -> Self {
+        Module {
+            magic: 0x6d736100,
+            version: 1,
+            sections: Vec::with_capacity(16),
+        }        
+    }
+}
+
 impl Module {
     /// New module with sections
     pub fn new(sections: Vec<Section>) -> Self {
         Module {
-            magic: 0x6d736100,
-            version: 1,
-            sections: sections,
+            sections: sections, ..Default::default()
         }
     }
 
+    /// Destructure the module, yielding sections
+    pub fn into_sections(self) -> Vec<Section> {
+        self.sections
+    }
+
     /// Version of module.
     pub fn version(&self) -> u32 { self.version }
 
@@ -57,6 +70,14 @@ impl Module {
         }
         None
     }
+
+    /// Functions signatures section, if any.
+    pub fn functions_section(&self) -> Option<&FunctionsSection> {
+        for section in self.sections() {
+            if let &Section::Function(ref sect) = section { return Some(sect); }
+        }
+        None        
+    }
 }
 
 impl Deserialize for Module {
diff --git a/src/elements/section.rs b/src/elements/section.rs
index 54a06c0..8fb6438 100644
--- a/src/elements/section.rs
+++ b/src/elements/section.rs
@@ -176,12 +176,20 @@ impl Serialize for Section {
     }
 }
 
+/// Section with type declarations
+#[derive(Default)]
 pub struct TypeSection(Vec<Type>);
 
 impl TypeSection {
+    /// List of type declarations
     pub fn types(&self) -> &[Type] {
         &self.0
     }
+
+    /// List of type declarations (mutable)
+    pub fn types_mut(&mut self) -> &mut Vec<Type> { 
+        &mut self.0
+    }
 }
 
 impl Deserialize for TypeSection {
@@ -215,6 +223,7 @@ impl Serialize for TypeSection {
 pub struct ImportSection(Vec<ImportEntry>);
 
 impl ImportSection {
+    /// List of import entries.
     pub fn entries(&self) -> &[ImportEntry] {
         &self.0
     }
@@ -248,17 +257,21 @@ impl Serialize for ImportSection {
 }
 
 /// Section with function signatures definition.
+#[derive(Default)]
 pub struct FunctionsSection(Vec<Func>);
 
 impl FunctionsSection {
+    /// New functions section
     pub fn new() -> FunctionsSection {
         FunctionsSection(Vec::new())
     }
 
+    /// List of all functions in the section, mutable
     pub fn entries_mut(&mut self) -> &mut Vec<Func> { 
         &mut self.0
     }
 
+    /// List of all functions in the section
     pub fn entries(&self) -> &[Func] {
         &self.0
     }
@@ -335,6 +348,7 @@ impl Serialize for TableSection {
 pub struct MemorySection(Vec<MemoryType>);
 
 impl MemorySection {
+    /// List of all memory entries in the section
     pub fn entries(&self) -> &[MemoryType] {
         &self.0
     }
@@ -371,6 +385,7 @@ impl Serialize for MemorySection {
 pub struct GlobalSection(Vec<GlobalEntry>);
 
 impl GlobalSection {
+    /// List of all global entries in the section
     pub fn entries(&self) -> &[GlobalEntry] {
         &self.0
     }
@@ -407,6 +422,7 @@ impl Serialize for GlobalSection {
 pub struct ExportSection(Vec<ExportEntry>);
 
 impl ExportSection {
+    /// List of all export entries in the section
     pub fn entries(&self) -> &[ExportEntry] {
         &self.0
     }
@@ -443,10 +459,12 @@ impl Serialize for ExportSection {
 pub struct CodeSection(Vec<FuncBody>);
 
 impl CodeSection {
+    /// New code section
     pub fn new(bodies: Vec<FuncBody>) -> Self {
         CodeSection(bodies)
     }
 
+    /// All function bodies in the section
     pub fn bodies(&self) -> &[FuncBody] {
         &self.0
     }
@@ -483,10 +501,12 @@ impl Serialize for CodeSection {
 pub struct ElementSection(Vec<ElementSegment>);
 
 impl ElementSection {
+    /// New elements section
     pub fn new(entries: Vec<ElementSegment>) -> Self {
         ElementSection(entries)
     }
 
+    /// New elements entries in the section
     pub fn entries(&self) -> &[ElementSegment] {
         &self.0
     }
@@ -523,10 +543,12 @@ impl Serialize for ElementSection {
 pub struct DataSection(Vec<DataSegment>);
 
 impl DataSection {
+    /// New data section
     pub fn new(segments: Vec<DataSegment>) -> Self {
         DataSection(segments)
     }
 
+    /// List of all data entries in the section
     pub fn entries(&self) -> &[DataSegment] {
         &self.0
     }
diff --git a/src/elements/types.rs b/src/elements/types.rs
index ac40061..e034f85 100644
--- a/src/elements/types.rs
+++ b/src/elements/types.rs
@@ -132,6 +132,14 @@ impl Default for FunctionType {
 }
 
 impl FunctionType {
+    /// New function type given the signature in-params(`params`) and return type (`return_type`)
+    pub fn new(params: Vec<ValueType>, return_type: Option<ValueType>) -> Self {
+        FunctionType {
+            params: params,
+            return_type: return_type,
+            ..Default::default()
+        }
+    }
     /// Function form (currently only valid value is `0x60`)
     pub fn form(&self) -> u8 { self.form }
     /// Parameters in the function signature.
diff --git a/src/lib.rs b/src/lib.rs
index 690bdcb..b5f2918 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,5 +10,7 @@ pub mod builder;
 pub use elements::{
     Error as SerializationError,
     deserialize_buffer, 
-    deserialize_file
+    deserialize_file,
+    serialize,
+    serialize_to_file,
 };