diff --git a/src/ast.rs b/src/ast.rs
index b5f8e04..1b0fdb6 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -11,9 +11,9 @@ impl IdGenerator {
         IdGenerator{counter: 0}
     }
 
-    pub fn next(&mut self) -> i64 {
+    pub fn next(&mut self) -> String {
         self.counter += 1;
-        self.counter
+        ("S" + self.counter.to_string()).to_string()
     }
 }
 
@@ -67,7 +67,7 @@ pub struct Spanned<T> {
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct FunctionTypeUsage {
     pub arguments: Vec<TypeUsage>,
-    pub return_type: TypeUsage,
+    pub return_type: Box<TypeUsage>,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
@@ -87,6 +87,38 @@ pub enum TypeUsage {
     Unknown(UnknownTypeUsage),
 }
 
+impl TypeUsage {
+    pub fn new_unknown(id_gen: &mut IdGenerator) -> TypeUsage {
+        return TypeUsage::Unknown(UnknownTypeUsage{
+            name: id_gen.next(),
+        });
+    }
+
+    pub fn new_named(identifier: &Identifier) -> TypeUsage {
+        return TypeUsage::Named(NamedTypeUsage{
+            name: identifier.clone(),
+        });
+    }
+
+    pub fn new_builtin(name: String) -> TypeUsage {
+        ast::TypeUsage::Named(ast::NamedTypeUsage{
+            name: ast::Identifier{
+                name: ast::Spanned{
+                    span: ast::Span{left: 0, right: 0}, //todo: figure out a sane value for these
+                    value: name,
+                }
+            }
+        )
+    }
+
+    pub fn new_function(arg_count: usize, id_gen: &mut IdGenerator) -> TypeUsage {
+        return TypeUsage::Function(FunctionTypeUsage{
+            arguments: 0..arg_count.map(|_| => TypeUsage.new_unknown(&mut id_gen)).collect(),
+            return_type: Box::new(TypeUsage.new_unknown(&mut id_gen)),
+        });
+    }
+}
+
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub enum Operator {
     Mul,
@@ -98,19 +130,20 @@ pub enum Operator {
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct LiteralInt {
     pub value: Spanned<i64>,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct LiteralFloat {
     pub value: Spanned<f64>,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct LiteralStruct {
+    pub name: Identifier,
     pub fields: HashMap<Identifier, Expression>,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
@@ -122,14 +155,14 @@ pub struct Identifier {
 pub struct FunctionCall {
     pub source: Expression,
     pub arguments: Vec<Expression>,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct StructGetter {
-    pub source: Box<Expression>,
+    pub source: Expression,
     pub attribute: Identifier,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
@@ -137,18 +170,20 @@ pub struct Operation {
     pub left: Expression,
     pub op: Operator,
     pub right: Expression,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct VariableUsage {
     pub name: Identifier,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub enum Subexpression {
     LiteralInt(LiteralInt),
+    LiteralFloat(LiteralFloat),
+    LiteralStruct(LiteralStruct),
     FunctionCall(FunctionCall),
     Identifier(Identifier),
     Op(Operation),
@@ -157,20 +192,19 @@ pub enum Subexpression {
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct Expression {
     pub subexpression: Spanned<Box<Subexpression>>,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct ReturnStatement {
     pub source: Expression,
-    pub type: TypeUsage,
-}
+};
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct LetStatement {
     variable_name: Identifier,
-    type: VariableUsage,
     expression: Expression,
+    type_: TypeUsage,
 }
 
 pub enum AssignmentTarget {
@@ -182,25 +216,26 @@ pub enum AssignmentTarget {
 pub struct AssignmentStatement {
     pub source: AssignmentTarget,
     pub expression: Expression,
-    pub type: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub enum Statement {
-    Assignment(Assignment),
+    Return(ReturnStatement),
+    Let(LetStatement),
+    Assignment(AssignmentStatement),
     Expression(Expression),
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct Block {
-    pub statements: Vec<Spanned<Statement>>,
-    pub type: TypeUsage,
+    pub statements: Vec<Statement>,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct VariableDeclaration {
     pub name: Identifier,
-    pub type: TypeUsage,
+    pub type_: TypeUsage,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
@@ -221,10 +256,16 @@ pub struct PrimitiveTypeDeclaration {
     pub name: String, // cannot be identifier as it's not declared anywhere specific, it's builtins
 }
 
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub struct StructField {
+    pub name: Identifier,
+    pub type_: TypeUsage,
+}
+
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct StructTypeDeclaration {
     pub name: Identifier,
-    pub fields: HashMap<Identifier, TypeUsage>,
+    pub fields: Vec<StructField>,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
@@ -241,14 +282,19 @@ pub enum TypeDeclaration {
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
-pub enum Impl {
+pub struct Impl {
     pub struct_name: Identifier,
     pub functions: Vec<Function>,
 }
 
 #[derive(Clone, PartialEq, Eq, Hash)]
-pub struct Module {
-    pub functions: Vec<Function>,
-    pub types: Vec<TypeDeclaration>,
-    pub impls: Vec<Impls>,
+pub enum ModuleItem {
+    Function(Function),
+    TypeDeclaration(TypeDeclaration),
+    Impl(Impl),
+}
+
+#[derive(Clone, PartialEq, Eq, Hash)]
+pub struct Module {
+    pub items: Vec<ModuleItem>,
 }
diff --git a/src/grammar.lalrpop b/src/grammar.lalrpop
index 1207f13..fcc650c 100644
--- a/src/grammar.lalrpop
+++ b/src/grammar.lalrpop
@@ -6,9 +6,9 @@ grammar(id_generator: ast::IdGenerator);
 
 
 pub TypeUsage: ast::TypeUsage = {
-    "fn" "(" <args:Comma<TypeUsage>> ")" => ast::TypeUsage::Function(ast::FunctionTypeUsage{arguments: args, return_type: ast::new_unit()}),
-    "fn" "(" <args:Comma<TypeUsage>> ")" ":" <return_type:TypeUsage> => ast::TypeUsage::Function(ast::FunctionTypeUsage{arguments: args, return_type: return_type),
-    <name:Identifier> => ast::TypeUsage::Named(ast::NamedTypeUsage{name: name})
+    "fn" "(" <args:Comma<TypeUsage>> ")" => ast::TypeUsage::Function(ast::FunctionTypeUsage{arguments: args, return_type: Box::new(ast::new_unit())}),
+    "fn" "(" <args:Comma<TypeUsage>> ")" ":" <return_type:TypeUsage> => ast::TypeUsage::Function(ast::FunctionTypeUsage{arguments: args, return_type: Box::new(return_type)),
+    <name:SpannedIdentifier> => ast::TypeUsage::Named(ast::NamedTypeUsage{name: name})
 };
 
 
@@ -17,7 +17,7 @@ pub LiteralInt: i64 = {
 };
 
 pub SpannedLiteralInt: ast::LiteralInt {
-    <literal_int:Spanned<LiteralInt>> => ast::LiteralInt{value: literal_int, type: ast::new_named("i64")},
+    <literal_int:Spanned<LiteralInt>> => ast::LiteralInt{value: literal_int, type_: ast::TypeUsage::new_builtin("i64")}
 };
 
 pub LiteralFloat: f64 = {
@@ -25,70 +25,150 @@ pub LiteralFloat: f64 = {
 };
 
 pub SpannedLiteralInt: ast::LiteralFloat {
-    <literal_float:Spanned<LiteralFloat>> => ast::LiteralFloat{value: literal_float, type: ast::new_named("f64")},
+    <literal_float:Spanned<LiteralFloat>> => ast::LiteralFloat{value: literal_float, type_: ast::TypeUsage::new_builtin("f64")}
 };
 
-pub Identifier: ast::Identifier = {
-    <i:r"[A-Za-z][A-Za-z0-9_]*"> => ast::Identifier{name: i.to_string()}
+pub Identifier: String = {
+    <i:r"[A-Za-z_][A-Za-z0-9_]*"> => i.to_string()
+};
+
+pub LiteralStructField: (String, Expression) {
+    <field:SpannedIdentifier> ":" <expr:Expression> => (field, expr)
+};
+
+pub LiteralStruct: ast::LiteralStruct {
+    <i:SpannedIdentifier> "{" <field_list:Comma<LiteralStructField>> "}" => LiteralStruct{
+        name: i,
+        fields: field_list.into_iter().collect(),
+        type_: ast::TypeUsage::new_named(i.clone()),
+    }
+};
+
+pub SpannedIdentifier: ast::Identifier {
+    <i:Spanned<Identifier>> => ast::Identifier{name: i}
 };
 
 pub FunctionCall: ast::FunctionCall = {
-    <i:Spanned<Identifier>> "(" <args:Comma<Spanned<Expression>>> ")" => ast::FunctionCall{name:i, arguments: args}
-}
+    <source:Expression> "(" <args:Comma<Expression>> ")" => ast::FunctionCall{source: source, arguments: args, type_: ast::TypeUsage::new_unknown(&mut id_generator)}
+};
 
-pub Expression: Box<ast::Expression> = {
-    <l:Spanned<Expression>> "+" <r:Spanned<Factor>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Plus, right: r})),
-    <l:Spanned<Expression>> "-" <r:Spanned<Factor>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Minus, right: r})),
+pub StructGetter: ast::StructGetter = {
+    <source:Expression> "." <field:SpannedIdentifier> => ast::StructGetter{source: source, attribute: field, type: ast::TypeUsage::new_unknown(&mut id_generator)}
+};
+
+pub VariableUsage: ast::VariableUsage = {
+    <identifier:SpannedIdentifier> => ast::VariableUsage{name: identifier, type_: ast::TypeUsage::new_unknown(&mut id_generator)}
+};
+
+pub Subxpression: Box<ast::Subexpression> = {
+    <l:Expression> "+" <r:Factor> => Box::new(ast::Subexpression::Op(ast::Operation{left: l, op: ast::Operator::Plus, right: r})),
+    <l:Expression> "-" <r:Factor> => Box::new(ast::Subexpression::Op(ast::Operation{left: l, op: ast::Operator::Minus, right: r})),
     Factor,
-}
+};
 
-pub Factor: Box<ast::Expression> = {
-    <l:Spanned<Factor>> "*" <r:Spanned<Term>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Mul, right: r})),
-    <l:Spanned<Factor>> "/" <r:Spanned<Term>> => Box::new(ast::Expression::Op(ast::Operation{left: l, op: ast::Operator::Div, right: r})),
+pub Factor: Box<ast::Subexpression> = {
+    <l:Factor> "*" <r:Term> => Box::new(ast::Subexpression::Op(ast::Operation{left: l, op: ast::Operator::Mul, right: r})),
+    <l:Factor> "/" <r:Term> => Box::new(ast::Subexpression::Op(ast::Operation{left: l, op: ast::Operator::Div, right: r})),
     Term,
-}
+};
 
-pub Term: Box<ast::Expression> = {
-    Spanned<LiteralInt> => Box::new(ast::Expression::LiteralInt(<>)),
-    Spanned<Identifier> => Box::new(ast::Expression::Identifier(<>)),
-    Spanned<FunctionCall> => Box::new(ast::Expression::FunctionCall(<>)),
-    "(" <e:Expression> ")" => e
-}
+pub Term: Box<ast::Subexpression> = {
+    SpannedLiteralInt => Box::new(ast::Subexpression::LiteralInt(<>)),
+    SpannedLiteralFloat => Box::new(ast::Subexpression::LiteralFloat(<>)),
+    SpannedLiteralStruct => Box::new(ast::Subexpression::LiteralStruct(<>)),
+    FunctionCall => Box::new(ast::Subexpression::FunctionCall(<>)),
+    Identifier => Box::new(ast::Subexpression::Identifier(<>)),
+    "(" <e:Expression> ")" => e.subexpression,
+};
 
-pub LetStatement: ast::Assignment = {
+pub Expression: ast::Expression = {
+    <sub:Subxpression> => ast::Expression{subexpression: sub, type_: ast::TypeUsage::new_unknown(&mut id_generator)}
+};
+
+pub ReturnStatement: ast::ReturnStatement = {
+    "return" <e:Expression> => ast::ReturnStatement{source: e}
+};
+
+pub LetStatement: ast::LetStatement = {
     //TODO: support destructuring with tuples, when they exist.
     //TODO: add mut, weak
-    "let" <n:Spanned<Identifier>> "=" <e:Spanned<Expression>> => ast::Assignment{name: n, type_usage: None, expression: e},
-    "let" <n:Spanned<Identifier>> ":" <t:Spanned<TypeUsage>> "=" <e:Spanned<Expression>> => ast::Assignment{name: n, type_usage: Some(t), expression: e},
+    "let" <n:SpannedIdentifier> "=" <e:Expression> => ast::LetStatement{variable_name: n, type_usage: ast::TypeUsage::new_unknown(&mut id_generator), expression: e},
+    "let" <n:SpannedIdentifier> ":" <t:TypeUsage> "=" <e:Expression> => ast::LetStatement{variable_name: n, type_usage: ast::TypeUsage::Named(ast::NamedTypeUsage{name: t}), expression: e},
+};
+
+pub AssignmentStatement: ast::AssignmentStatement {
+    <v:VariableUsage> "=" <e:Expression> => ast::AssignmentStatement{source: ast::AssignmentTarget::Variable(v), expression: e},
+    <sg:StructGetter> "=" <e:Expression> => ast::AssignmentStatement{source: ast::AssignmentTarget::StructAttr(sg), expression: e},
 }
 
 pub Statement: ast::Statement = {
-    <l:Spanned<LetStatement>> => ast::Statement::Assignment(l),
-    <e:Spanned<Expression>> => ast::Statement::Expression(e),
+    <r:ReturnStatement> ";" => ast::Statement::Return(r),
+    <l:LetStatement> ";" => ast::Statement::Let(l),
+    <a:AssignmentStatement> ";" => ast::Statement::Assignment(l),
+    <e:Expression> ";" => ast::Statement::Expression(e),
 }
 
 pub Block: ast::Block = {
-    "{" <s:LineDelimiter<Spanned<Statement>>> "}" => ast::Block{statements: s}
+    "{" <v:(Statement ";")*> <e:Expression?> "}" => match e {
+        None => ast::Block{statements: s, type_: ast::new_never()},
+        Some(e) => {
+            let mut v = v;
+            v.push(ast::Statement::Expression(e));
+            ast::Block{statements: v, type_: ast::TypeUsage::new_unknown(&mut id_generator)}
+        }
+    }
 }
 
 pub TypeUsage: ast::TypeUsage = {
-    <n:Spanned<Identifier>> => ast::TypeUsage{name: n, ty: types::SpecifiedType::Unknown}
+    <n:SpannedIdentifier> => ast::TypeUsage::Named(ast::NamedTypeUsage{name: n}),
+    "fn" "(" <args:Comma<TypeUsage>> ")" => ast::TypeUsage::Function(ast::FunctionTypeUsage{arguments: args, return_type: Box::new(ast::TypeUsage::new_unknown(&mut id_generator))}),
+    "fn" "(" <args:Comma<TypeUsage>> ")" ":" <rt:TypeUsage> => ast::TypeUsage::Function(ast::FunctionTypeUsage{arguments: args, return_type: Box::new(rt)}),
 }
 
 pub VariableDeclaration: ast::VariableDeclaration = {
-    <i:Spanned<Identifier>> ":" <t:Spanned<TypeUsage>> => ast::VariableDeclaration{name: i, type_usage: t},
+    <i:SpannedIdentifier> ":" <t:TypeUsage> => ast::VariableDeclaration{name: i, type_usage: t},
+}
+
+pub FunctionDeclaration: ast::FunctionDeclaration {
+    "fn" <n:SpannedIdentifier> "(" <args:Comma<VariableDeclaration>> ")" => ast::FunctionDeclaration{name: n, arguments: args, return_type: ast::TypeUsage::new_unknown(&mut id_generator)},
+    "fn" <n:SpannedIdentifier> "(" <args:Comma<VariableDeclaration>> ")" ":" <rt:TypeUsage> => ast::FunctionDeclaration{name: n, arguments: args, return_type: rt},
 }
 
 pub Function: ast::Function = {
-    "fn" <n:Spanned<Identifier>> "(" <args:Comma<VariableDeclaration>> ")" <rt:Spanned<TypeUsage>> <b:Block> => ast::Function{name: n, arguments: args, block: b, return_type: rt}
+    <d:FunctionDeclaration> <b:Block> => ast::Function{declaration: d, block: b}
 }
 
+pub StructField: ast::StructField = {
+    <i:SpannedIdentifier> ":" <t:TypeUsage> => (i, t),
+}
+
+pub StructTypeDeclaration: ast::StructTypeDeclaration {
+    "type" <i:SpannedIdentifier> "struct" "{" Comma<StructField> "}"
+}
+
+pub TypeAliasDeclaration: ast::TypeAliasDeclaration {
+    "type" <i:SpannedIdentifier> "=" <t:TypeUsage> ";" => ast::AliasTypeDeclaration{name: i, replaces: t}
+}
+
+pub TypeDeclaration: ast::TypeDeclaration {
+    <s:StructTypeDeclaration> => ast::TypeDeclaration::Struct(s),
+    <a:AliasTypeDeclaration> => ast::TypeDeclaration::Alias(a),
+}
+
+pub Impl: ast::Impl {
+    "impl" <i:SpannedIdentifier> "{" <f:Function*> "}" => ast::Impl{struct_name: i, functions: s}
+}
+
+pub ModuleItem: ast::ModuleItem {
+    <f:Function> => ast::ModuleItem::Function(f),
+    <td:TypeDeclaration> => ast::ModuleItem::TypeDeclaration(td),
+    <i:Impl> => ast::ModuleItem::Impl(i),
+}
 
 pub Module: ast::Module = {
-    <fs:Function*> => ast::Module{functions: fs}
+    <i:ModuleItem*> => ast::Module{items: i}
 }
 
-
 // From https://lalrpop.github.io/lalrpop/tutorial/006_macros.html
 // Comma seperated list of T with optional trailing comma
 Comma<T>: Vec<T> = {
@@ -102,16 +182,6 @@ Comma<T>: Vec<T> = {
     }
 };
 
-
-LineDelimiter<T>: Vec<T> = {
-    <v:(<T> r"\n|;")*> <e:T> => {
-        let mut v = v;
-        v.push(e);
-        v
-    }
-};
-
-
 Spanned<Rule>: ast::Spanned<Rule> = {
   <l: @L> <rule: Rule> <r: @R> => ast::Spanned{span: ast::Span{left: l, right: r}, value: rule}
 };