diff --git a/src/ast/build.rs b/src/ast/build.rs
index 3e35eec..faf5ed6 100644
--- a/src/ast/build.rs
+++ b/src/ast/build.rs
@@ -1,12 +1,15 @@
 use crate::ast::{
-    ClassConstructor, ClassConstructorParameter, ClassDeclaration, ClassLevelDeclaration,
-    CompilationUnit, FieldDeclaration, FullyQualifiedName, FunctionDefinition,
-    FunctionTypeModifier, FunctionTypeUse, GenericArguments, GenericParameter, GenericParameters,
-    Identifier, ImplementsList, InterfaceDeclaration, InterfaceFunctionDeclaration,
-    InterfaceLevelDeclaration, InterfaceOperatorFunctionDeclaration, InterfaceOrClassTypeUse,
-    ModuleDeclaration, ModuleLevelDeclaration, OperatorFunctionDefinition, Parameters,
-    PlatformFunctionDeclaration, PropertyDeclaration, Reference, References, ReturnType,
-    TupleArguments, TupleTypeUse, TypeUse,
+    AssignStatement, BinaryExpression, BinaryOperator, BlockStatement, CallStatement,
+    ClassConstructor, ClassConstructorParameter, ClassDeclaration, ClassLevelDeclaration, Closure,
+    CompilationUnit, Expression, FieldDeclaration, ForStatement, FullyQualifiedName, FunctionBody,
+    FunctionDefinition, FunctionModifier, FunctionTypeModifier, FunctionTypeUse, GenericArguments,
+    GenericParameter, GenericParameters, Identifier, IfElseStatement, IfStatement, ImplementsList,
+    InterfaceDeclaration, InterfaceFunctionDeclaration, InterfaceLevelDeclaration,
+    InterfaceOperatorFunctionDeclaration, InterfaceOrClassTypeUse, Literal, ModuleDeclaration,
+    ModuleLevelDeclaration, OperatorFunctionDefinition, Parameter, Parameters,
+    PlatformFunctionDeclaration, PropertyDeclaration, Reference, References, ReturnStatement,
+    ReturnType, Statement, TernaryExpression, TupleArguments, TupleTypeUse, TypeUse,
+    VariableDeclarationStatement, WhileStatement,
 };
 use crate::parser::Rule;
 use pest::iterators::Pair;
@@ -42,6 +45,7 @@ fn build_fqn(fqn_pair: Pair<Rule>) -> FullyQualifiedName {
 fn build_type_use(type_use_pair: Pair<Rule>) -> TypeUse {
     let inner_pair = type_use_pair.into_inner().next().unwrap();
     match inner_pair.as_rule() {
+        Rule::Void => TypeUse::Void,
         Rule::InterfaceOrClassTypeUse => {
             TypeUse::InterfaceOrClass(build_interface_or_class_type_use(inner_pair))
         }
@@ -211,12 +215,23 @@ fn build_function_type_modifier(pair: Pair<Rule>) -> FunctionTypeModifier {
     }
 }
 
-fn build_parameters(pair: Pair<Rule>) -> Parameters {
-    todo!()
+fn build_parameters(parameters_pair: Pair<Rule>) -> Parameters {
+    Parameters(
+        parameters_pair
+            .into_inner()
+            .map(|parameter_pair| expect_and_use(parameter_pair, Rule::Parameter, build_parameter))
+            .collect(),
+    )
 }
 
-fn build_parameter(pair: Pair<Rule>) -> Parameters {
-    todo!()
+fn build_parameter(parameter_pair: Pair<Rule>) -> Parameter {
+    let mut inner = parameter_pair.into_inner();
+    let identifier = expect_and_use(inner.next().unwrap(), Rule::Identifier, build_identifier);
+    let type_use = expect_and_use(inner.next().unwrap(), Rule::TypeUse, build_type_use);
+    Parameter {
+        identifier,
+        type_use,
+    }
 }
 
 fn build_return_type(return_type_pair: Pair<Rule>) -> ReturnType {
@@ -289,7 +304,7 @@ fn build_module_level_declaration(pair: Pair<Rule>) -> ModuleLevelDeclaration {
         }
         Rule::Class => ModuleLevelDeclaration::Class(build_class_declaration(inner_pair)),
         Rule::FunctionDefinition => {
-            ModuleLevelDeclaration::Function(build_function_declaration(inner_pair))
+            ModuleLevelDeclaration::Function(build_function_definition(inner_pair))
         }
         Rule::PlatformFunction => ModuleLevelDeclaration::PlatformFunction(
             build_platform_function_declaration(inner_pair),
@@ -331,7 +346,7 @@ fn build_class_level_declaration(declaration_pair: Pair<Rule>) -> ClassLevelDecl
         }
         Rule::Class => ClassLevelDeclaration::Class(build_class_declaration(inner_pair)),
         Rule::FunctionDefinition => {
-            ClassLevelDeclaration::Function(build_function_declaration(inner_pair))
+            ClassLevelDeclaration::Function(build_function_definition(inner_pair))
         }
         Rule::OperatorFunctionDefinition => {
             ClassLevelDeclaration::OperatorFunction(build_operator_function_declaration(inner_pair))
@@ -454,8 +469,52 @@ fn build_class_declaration(class_pair: Pair<Rule>) -> ClassDeclaration {
     }
 }
 
-fn build_function_declaration(function_definition_pair: Pair<Rule>) -> FunctionDefinition {
-    todo!()
+fn build_function_definition(function_definition_pair: Pair<Rule>) -> FunctionDefinition {
+    let mut is_public = false;
+    let mut modifier = None;
+    let mut generics = None;
+    let mut identifier = None;
+    let mut parameters = None;
+    let mut return_type = None;
+    let mut body = None;
+
+    for inner_pair in function_definition_pair.into_inner() {
+        match inner_pair.as_rule() {
+            Rule::Pub => {
+                is_public = true;
+            }
+            Rule::FunctionModifier => {
+                modifier = Some(build_function_modifier(inner_pair));
+            }
+            Rule::Fn => {}
+            Rule::GenericParameters => {
+                generics = Some(build_generic_parameters(inner_pair));
+            }
+            Rule::Identifier => {
+                identifier = Some(build_identifier(inner_pair));
+            }
+            Rule::Parameters => {
+                parameters = Some(build_parameters(inner_pair));
+            }
+            Rule::ReturnType => {
+                return_type = Some(build_return_type(inner_pair));
+            }
+            Rule::FunctionBody => {
+                body = Some(build_function_body(inner_pair));
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    FunctionDefinition {
+        is_public,
+        modifier,
+        generics: generics.unwrap_or_else(GenericParameters::default),
+        identifier: identifier.unwrap(),
+        parameters: parameters.unwrap(),
+        return_type: return_type.unwrap_or_else(ReturnType::void),
+        body: body.unwrap(),
+    }
 }
 
 fn build_operator_function_declaration(
@@ -510,6 +569,43 @@ fn build_class_constructor(class_constructor_pair: Pair<Rule>) -> ClassConstruct
     )
 }
 
+fn build_function_modifier(modifier_pair: Pair<Rule>) -> FunctionModifier {
+    let mut inner = modifier_pair.into_inner();
+    if inner.len() == 2 {
+        FunctionModifier::MutRef
+    } else {
+        match inner.next().unwrap().as_rule() {
+            Rule::Static => FunctionModifier::Static,
+            Rule::Cons => FunctionModifier::Cons,
+            Rule::Mut => FunctionModifier::Mut,
+            Rule::Ref => FunctionModifier::Ref,
+            _ => unreachable!(),
+        }
+    }
+}
+
+fn build_function_body(body_pair: Pair<Rule>) -> FunctionBody {
+    let inner_pair = body_pair.into_inner().next().unwrap();
+    match inner_pair.as_rule() {
+        Rule::FunctionEqualsBody => FunctionBody::Equals(expect_and_use(
+            inner_pair.into_inner().next().unwrap(),
+            Rule::Expression,
+            build_expression,
+        )),
+        Rule::BlockStatement => FunctionBody::Block(build_block_statement(inner_pair)),
+        Rule::FunctionAliasBody => {
+            let mut alias_body_pairs = inner_pair.into_inner();
+            alias_body_pairs.next().unwrap(); // Alias
+            FunctionBody::Alias(expect_and_use(
+                alias_body_pairs.next().unwrap(),
+                Rule::Identifier,
+                build_identifier,
+            ))
+        }
+        _ => unreachable!(),
+    }
+}
+
 fn build_property_class_constructor_parameter(
     property_pair: Pair<Rule>,
 ) -> ClassConstructorParameter {
@@ -574,3 +670,166 @@ fn build_field_declaration(field_pair: Pair<Rule>) -> FieldDeclaration {
         declared_type: declared_type.unwrap(),
     }
 }
+
+fn build_block_statement(block_statement_pair: Pair<Rule>) -> BlockStatement {
+    let mut statements = vec![];
+    let mut expression = None;
+
+    for inner_pair in block_statement_pair.into_inner() {
+        match inner_pair.as_rule() {
+            Rule::Statement => {
+                statements.push(build_statement(inner_pair));
+            }
+            Rule::Expression => {
+                expression = Some(build_expression(inner_pair));
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    BlockStatement {
+        statements,
+        expression,
+    }
+}
+
+fn build_statement(statement_pair: Pair<Rule>) -> Statement {
+    let first = statement_pair.into_inner().next().unwrap();
+    match first.as_rule() {
+        Rule::BlockStatement => Statement::BlockStatement(build_block_statement(first)),
+        Rule::VariableDeclaration => {
+            Statement::VariableDeclarationStatement(build_variable_declaration(first))
+        }
+        Rule::AssignmentStatement => Statement::AssignStatement(build_assignment_statement(first)),
+        Rule::CallStatement => Statement::CallStatement(build_call_statement(first)),
+        Rule::ReturnStatement => Statement::ReturnStatement(build_return_statement(first)),
+        Rule::IfStatement => Statement::IfStatement(build_if_statement(first)),
+        Rule::IfElseStatement => Statement::IfElseStatement(build_if_else_statement(first)),
+        Rule::WhileStatement => Statement::WhileStatement(build_while_statement(first)),
+        Rule::ForStatement => Statement::ForStatement(build_for_statement(first)),
+        _ => unreachable!(),
+    }
+}
+
+fn build_variable_declaration(
+    variable_declaration_pair: Pair<Rule>,
+) -> VariableDeclarationStatement {
+    todo!()
+}
+
+fn build_assignment_statement(assignment_pair: Pair<Rule>) -> AssignStatement {
+    todo!()
+}
+
+fn build_call_statement(call_statement_pair: Pair<Rule>) -> CallStatement {
+    todo!()
+}
+
+fn build_return_statement(return_statement_pair: Pair<Rule>) -> ReturnStatement {
+    todo!()
+}
+
+fn build_if_statement(if_statement_pair: Pair<Rule>) -> IfStatement {
+    todo!()
+}
+
+fn build_if_else_statement(if_else_statement_pair: Pair<Rule>) -> IfElseStatement {
+    todo!()
+}
+
+fn build_while_statement(while_statement_pair: Pair<Rule>) -> WhileStatement {
+    todo!()
+}
+
+fn build_for_statement(for_statement_pair: Pair<Rule>) -> ForStatement {
+    todo!()
+}
+
+fn build_expression(expression_pair: Pair<Rule>) -> Expression {
+    let inner_pair = expression_pair.into_inner().next().unwrap();
+    match inner_pair.as_rule() {
+        Rule::TernaryExpression => Expression::Ternary(build_ternary_expression(inner_pair)),
+        Rule::OrExpression => build_or_expression(inner_pair),
+        _ => unreachable!(),
+    }
+}
+
+fn build_ternary_expression(ternary_pair: Pair<Rule>) -> TernaryExpression {
+    todo!()
+}
+
+fn build_or_expression(or_expression_pair: Pair<Rule>) -> Expression {
+    let mut inner = or_expression_pair.into_inner();
+    if inner.len() == 3 {
+        let left = expect_and_use(
+            inner.next().unwrap(),
+            Rule::AndExpression,
+            build_and_expression,
+        );
+        inner.next().unwrap(); // Or
+        let right = expect_and_use(inner.next().unwrap(), Rule::Expression, build_expression);
+        Expression::Binary(BinaryExpression {
+            left: Box::new(left),
+            operator: BinaryOperator::Or,
+            right: Box::new(right),
+        })
+    } else {
+        build_and_expression(inner.next().unwrap())
+    }
+}
+
+fn build_and_expression(and_expression_pair: Pair<Rule>) -> Expression {
+    todo!()
+}
+
+fn build_equality_expression(equality_pair: Pair<Rule>) -> Expression {
+    todo!()
+}
+
+fn build_comparison_expression(comparison_expression_pair: Pair<Rule>) -> Expression {
+    todo!()
+}
+
+fn build_shift_expression(shift_expression_pair: Pair<Rule>) -> Expression {
+    todo!()
+}
+
+fn build_additive_expression(add_expression_pair: Pair<Rule>) -> Expression {
+    todo!()
+}
+
+fn build_multiplicative_expression(multiplicative_expression_pair: Pair<Rule>) -> Expression {
+    todo!()
+}
+
+fn build_unary_expression(unary_expression_pair: Pair<Rule>) -> Expression {
+    todo!()
+}
+
+fn build_primary_expression(primary_expression_pair: Pair<Rule>) -> Expression {
+    let mut inner = primary_expression_pair.into_inner();
+    let first_pair = inner.next().unwrap();
+    let expression = match first_pair.as_rule() {
+        Rule::Literal => Expression::Literal(build_literal(first_pair)),
+        Rule::FullyQualifiedName => Expression::FullyQualifiedName(build_fqn(first_pair)),
+        Rule::Closure => Expression::Closure(build_closure(first_pair)),
+        Rule::ParenthesizedExpression => {
+            let inner_expression = first_pair.into_inner().next().unwrap();
+            expect_and_use(inner_expression, Rule::Expression, build_expression)
+        }
+        _ => unreachable!(),
+    };
+    if let Some(suffix_pair) = inner.next() {
+        todo!()
+    } else {
+        expression
+    }
+}
+
+fn build_literal(literal_pair: Pair<Rule>) -> Literal {
+    todo!()
+}
+
+fn build_closure(closure_pair: Pair<Rule>) -> Closure {
+    todo!()
+}
diff --git a/src/ast/mod.rs b/src/ast/mod.rs
index d0c333a..bbef193 100644
--- a/src/ast/mod.rs
+++ b/src/ast/mod.rs
@@ -60,6 +60,7 @@ pub struct FullyQualifiedName(pub Vec<Identifier>);
 
 #[derive(Debug)]
 pub enum TypeUse {
+    Void,
     InterfaceOrClass(InterfaceOrClassTypeUse),
     Tuple(TupleTypeUse),
     Function(FunctionTypeUse),
@@ -189,6 +190,17 @@ pub struct ReturnType {
     pub references: References,
 }
 
+impl ReturnType {
+    pub fn void() -> Self {
+        ReturnType {
+            declared_type: Box::new(TypeUse::Void),
+            references: References::default()
+        }
+    }
+}
+
+/* References */
+
 #[derive(Debug)]
 pub struct References(pub Vec<Reference>);
 
@@ -373,14 +385,17 @@ pub struct FieldDeclaration {
 // Statements
 
 #[derive(Debug)]
-pub struct BlockStatement(pub Vec<Statement>);
+pub struct BlockStatement {
+    pub statements: Vec<Statement>,
+    pub expression: Option<Expression>,
+}
 
 #[derive(Debug)]
 pub enum Statement {
     BlockStatement(BlockStatement),
     VariableDeclarationStatement(VariableDeclarationStatement),
     AssignStatement(AssignStatement),
-    CallStatement(CallExpression),
+    CallStatement(CallStatement),
     ReturnStatement(ReturnStatement),
     IfStatement(IfStatement),
     IfElseStatement(IfElseStatement),
@@ -397,7 +412,16 @@ pub struct VariableDeclarationStatement {
 }
 
 #[derive(Debug)]
-pub struct AssignStatement(pub AssignmentExpression);
+pub struct AssignStatement {
+    pub lhs: Expression,
+    pub rhs: Expression,
+}
+
+#[derive(Debug)]
+pub struct CallStatement {
+    pub callee: Expression,
+    pub arguments: CallArguments
+}
 
 #[derive(Debug)]
 pub struct ReturnStatement(pub Option<Expression>);
@@ -439,8 +463,10 @@ pub enum Expression {
     Ternary(TernaryExpression),
     Binary(BinaryExpression),
     Unary(UnaryExpression),
-    Assignment(Box<AssignmentExpression>),
     Call(CallExpression),
+    FullyQualifiedName(FullyQualifiedName),
+    Closure(Closure),
+    ObjectAccess(ObjectAccess),
     Literal(Literal),
 }
 
@@ -465,12 +491,6 @@ pub struct UnaryExpression {
     pub rhs_operators: Vec<SuffixUnaryOperator>,
 }
 
-#[derive(Debug)]
-pub struct AssignmentExpression {
-    identifier: Identifier,
-    expression: Expression,
-}
-
 #[derive(Debug)]
 pub struct CallExpression {
     pub callee: Box<Expression>,
@@ -483,6 +503,26 @@ pub struct CallArguments(pub Vec<CallArgument>);
 #[derive(Debug)]
 pub struct CallArgument(pub Box<Expression>);
 
+#[derive(Debug)]
+pub struct Closure {
+    
+}
+
+#[derive(Debug)]
+pub struct ObjectAccess {
+    pub receiver: Box<Expression>,
+    pub navigations: ObjectNavigations
+}
+
+#[derive(Debug)]
+pub struct ObjectNavigations(pub Vec<ObjectNavigation>);
+
+#[derive(Debug)]
+pub enum ObjectNavigation {
+    Index(Box<Expression>),
+    Identifier(Box<Identifier>)
+}
+
 #[derive(Debug)]
 pub enum Literal {
     IntegerLiteral(i32),
diff --git a/src/parser/deimos.pest b/src/parser/deimos.pest
index ec87955..55a4a39 100644
--- a/src/parser/deimos.pest
+++ b/src/parser/deimos.pest
@@ -27,6 +27,7 @@ While = { "while" }
 For = { "for" }
 In = { "in" }
 Move = { "move" }
+Alias = { "alias" }
 
 // Keywords as a rule (for preventing identifiers with keywords, etc.)
 Keyword = {
@@ -58,6 +59,7 @@ Keyword = {
     | For
     | In
     | Move
+    | Alias
 }
 
 // Symbols
@@ -168,7 +170,8 @@ ParenthesesOptionalTypeUseList = {
 // Parameters = declaration
 
 TypeUse = {
-      InterfaceOrClassTypeUse
+      Void
+    | InterfaceOrClassTypeUse
     | TupleTypeUse
     | FunctionTypeUse
 }
@@ -433,7 +436,7 @@ FunctionEqualsBody = {
 }
 
 FunctionAliasBody = {
-      "alias"
+      Alias
     ~ Identifier
 }
 
@@ -504,7 +507,15 @@ AssignmentStatement = {
     ~ Expression
 }
 
-CallStatement = { PrimaryExpression }
+CallStatement = { 
+      (
+          Literal
+        | FullyQualifiedName
+        | Closure
+        | ParenthesizedExpression
+      )
+    ~ ( ObjectAccess? ~ ParenthesesCall )+
+}
 
 ReturnStatement = {
       Return
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index 7783166..4d20567 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -8,7 +8,7 @@ pub struct DeimosParser;
 mod deimos_parser_tests {
     use crate::parser::{DeimosParser, Rule};
     use pest::iterators::Pair;
-    use pest::{parses_to, Parser};
+    use pest::{Parser};
 
     macro_rules! fail_rule {
         ($pair: expr; $rule:path) => {{