diff --git a/sketching/april_2025/closure_inputs.dm b/sketching/april_2025/closure_inputs.dm
new file mode 100644
index 0000000..4185c3f
--- /dev/null
+++ b/sketching/april_2025/closure_inputs.dm
@@ -0,0 +1,16 @@
+class Counter {
+    fld count: Int
+
+    mut getAndIncrement() -> Int {
+        let result = count
+        count++
+        result
+    }
+}
+
+@Synthetic
+class MyClosure(delegate: Counter) : MutClosure(Int, Int) -> Int |delegate| {
+    mut fn call(x: Int, y: Int) -> Int {
+        x + y + delegate.getAndIncrement()
+    }
+}
diff --git a/sketching/april_2025/iterator.dm b/sketching/april_2025/iterator.dm
new file mode 100644
index 0000000..d562b0d
--- /dev/null
+++ b/sketching/april_2025/iterator.dm
@@ -0,0 +1,14 @@
+pub type Iterator<T> |backing: &Any| = mut fn () -> Option<&T ref backing>
+
+pub int Iterable<T> {
+    ref fn iterator() -> Iterator<T>(&self)
+}
+
+fn main() {
+    let nums: List<Int> = [1, 2, 3]
+    let iterator: Iterator<Int> |backing = nums| = nums.iterator()
+    let first: &Int ref nums = iterator().unwrap()
+    let second: &Int ref nums = iterator().unwrap()
+    let third: &Int ref nums = iterator().unwrap()
+    println "${*first}, ${*second}, ${*third}"
+}
diff --git a/src/ast/mod.rs b/src/ast/mod.rs
index 4e8565b..f5deaa6 100644
--- a/src/ast/mod.rs
+++ b/src/ast/mod.rs
@@ -1,256 +1,507 @@
-use crate::vm::source_code_location::SourceCodeLocation;
 use pest::Parser;
 
 pub mod build;
+pub mod unparse;
+
+// Operators
 
 #[derive(Debug)]
-pub struct CompilationUnit {
-    namespace: Option<Fqn>,
-    declarations: Vec<Declaration>,
+pub enum Operator {
+    Binary(BinaryOperator),
+    Unary(UnaryOperator),
 }
 
-impl CompilationUnit {
-    pub fn namespace(&self) -> &Option<Fqn> {
-        &self.namespace
-    }
+#[derive(Debug)]
+pub enum BinaryOperator {
+    Or,
+    And,
+    EqualTo,
+    NotEqualTo,
+    Greater,
+    Less,
+    GreaterEqual,
+    LessEqual,
+    Add,
+    Subtract,
+    Multiply,
+    Divide,
+    Modulo,
+    LeftShift,
+    RightShift,
+}
 
-    pub fn declarations(&self) -> &Vec<Declaration> {
-        &self.declarations
-    }
+#[derive(Debug)]
+pub enum UnaryOperator {
+    Not,
+    Negative,
+    PlusPlus,
+    MinusMinus,
+    CallOp,
+    Spread,
+}
+
+// Names
+
+#[derive(Debug, Clone)]
+pub struct Identifier {
+    pub name: String,
 }
 
 #[derive(Debug)]
 pub struct Fqn {
-    identifiers: Vec<Identifier>,
+    pub identifiers: Vec<Identifier>,
 }
 
-impl Fqn {
-    pub fn new(identifiers: Vec<Identifier>) -> Self {
-        Fqn { identifiers }
-    }
-
-    pub fn identifiers(&self) -> &Vec<Identifier> {
-        &self.identifiers
-    }
-
-    pub fn push_identifier(&mut self, identifier: Identifier) {
-        self.identifiers.push(identifier);
-    }
-
-    pub fn pop_identifier(&mut self) {
-        self.identifiers.pop();
-    }
-}
+// Generic parameters
 
 #[derive(Debug)]
-pub enum Declaration {
-    Interface {
-        identifier: Identifier,
-        is_extern: bool,
-        is_public: bool,
-        type_declaration: TypeDeclaration,
-    },
-    Implementation {
-        identifier: Identifier,
-        is_extern: bool,
-        is_public: bool,
-        type_declaration: TypeDeclaration,
-        impl_ctor: Option<ClassConstructor>,
-    },
-    Module {
-        identifier: Identifier,
-        is_extern: bool,
-        is_public: bool,
-        declarations: Vec<Declaration>,
-    },
-    Function(FunctionDeclaration),
-    Prop(Prop),
-    Field(Field),
-}
+pub struct GenericParameters(pub Vec<GenericParameter>);
 
-#[derive(Debug)]
-pub struct FunctionDeclaration {
-    source_code_location: SourceCodeLocation,
-    identifier: Identifier,
-    is_extern: bool,
-    is_public: bool,
-    parameters: Vec<Parameter>,
-    declared_type: Option<TypeUse>,
-    block_statement: BlockStatement,
-}
-
-impl FunctionDeclaration {
-    pub fn source_code_location(&self) -> &SourceCodeLocation {
-        &self.source_code_location
-    }
-
-    pub fn identifier(&self) -> &Identifier {
-        &self.identifier
-    }
-
-    pub fn block_statement(&self) -> &BlockStatement {
-        &self.block_statement
-    }
-}
-
-#[derive(Debug)]
-pub struct TypeDeclaration {
-    generics: Vec<GenericParameter>,
-    extends: Vec<TypeUse>,
-    declarations: Vec<Declaration>,
-}
-
-impl TypeDeclaration {
-    pub fn new(
-        generics: Vec<GenericParameter>,
-        extends: Vec<TypeUse>,
-        declarations: Vec<Declaration>,
-    ) -> TypeDeclaration {
-        TypeDeclaration {
-            generics,
-            extends,
-            declarations,
-        }
-    }
-}
-
-#[derive(Debug, Clone)]
-pub struct Identifier {
-    name: String,
-}
-
-impl Identifier {
-    pub fn name(&self) -> &str {
-        &self.name
+impl GenericParameters {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
     }
 }
 
 #[derive(Debug)]
 pub struct GenericParameter {
     identifier: Identifier,
-    bound: Option<GenericBound>,
 }
 
+// Generic arguments
+
 #[derive(Debug)]
-pub enum GenericBound {
-    Extends { fqn: Fqn },
-    Super { fqn: Fqn },
+pub struct GenericArguments(pub Vec<GenericArgument>);
+
+impl GenericArguments {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
 }
 
 #[derive(Debug)]
 pub struct GenericArgument {
-    fqn: Fqn,
+    pub fqn: Fqn,
 }
 
+// Type-use and components
+
 #[derive(Debug)]
 pub struct TypeUse {
-    fqn: Fqn,
-    generics: Vec<GenericArgument>,
+    pub fqn: Fqn,
+    pub arguments: Option<TypeArguments>,
 }
 
 #[derive(Debug)]
-pub struct ClassConstructor {
-    args: Vec<ClassMember>,
+pub enum TypeArguments {
+    Generics(GenericArguments),
+    Tuple(TupleArguments),
+    Function(FunctionTypeArguments),
 }
 
-impl ClassConstructor {
-    pub fn new(args: Vec<ClassMember>) -> Self {
-        ClassConstructor { args }
+#[derive(Debug)]
+pub struct TupleArguments(pub Vec<Fqn>);
+
+impl TupleArguments {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
     }
 }
 
 #[derive(Debug)]
-pub struct ClassMember {
-    is_field: bool,
-    identifier: Identifier,
-    type_use: Option<TypeUse>
+pub struct FunctionTypeArguments {
+    pub parameters: Parameters,
+    pub return_type: Box<TypeUse>,
 }
 
-impl ClassMember {
-    pub fn new(is_field: bool, identifier: Identifier, type_use: Option<TypeUse>) -> Self {
-        ClassMember {
-            is_field,
-            identifier,
-            type_use
-        }
+// Function components
+
+#[derive(Debug)]
+pub struct Parameters(pub Vec<Parameter>);
+
+impl Parameters {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
     }
 }
 
 #[derive(Debug)]
-pub struct ImplCtorArg {
-    is_field: bool,
+pub struct Parameter {
     identifier: Identifier,
-    r#type: Option<TypeUse>,
+    type_use: TypeUse,
 }
 
 #[derive(Debug)]
-pub struct Prop {
-    identifier: Identifier,
-    r#type: TypeUse,
+pub struct ReturnType {
+    pub type_use: Box<TypeUse>,
+    pub references: References,
 }
 
 #[derive(Debug)]
-pub struct Field {
-    identifier: Identifier,
-    r#type: TypeUse,
-}
+pub struct References(pub Vec<Reference>);
 
-#[derive(Debug)]
-pub struct BlockStatement {
-    statements: Vec<Statement>,
-}
-
-impl BlockStatement {
-    pub fn statements(&self) -> &Vec<Statement> {
-        &self.statements
+impl References {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
     }
 }
 
+#[derive(Debug)]
+pub struct Reference {
+    pub identifier: Identifier,
+}
+
+// Inputs
+
+#[derive(Debug)]
+pub enum DelegateOrIdentifier {
+    Delegate,
+    Identifier(Identifier),
+}
+
+#[derive(Debug)]
+pub struct InputParameters(pub Vec<DelegateOrIdentifier>);
+
+impl InputParameters {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+#[derive(Debug)]
+pub struct InputArguments(pub Vec<InputArgument>);
+
+impl InputArguments {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+#[derive(Debug)]
+pub struct InputArgument {
+    pub lhs: DelegateOrIdentifier,
+    pub rhs: Identifier
+}
+
+// Where guards
+
+#[derive(Debug)]
+pub struct WhereGuards(pub Vec<WhereGuard>);
+
+impl WhereGuards {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+#[derive(Debug)]
+pub struct WhereGuard {
+    pub identifier: Identifier,
+    pub implements: ImplementsList
+}
+
+// Implements
+
+#[derive(Debug)]
+pub struct ImplementsList(pub Vec<TypeUse>);
+
+impl ImplementsList {
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+}
+
+// Top-level construct
+
+#[derive(Debug)]
+pub struct CompilationUnit {
+    pub namespace: Option<Fqn>,
+    pub declarations: Vec<ModuleLevelDeclaration>,
+}
+
+// Declarations allowed in each level
+
+#[derive(Debug)]
+pub enum ModuleLevelDeclaration {
+    Type(TypeDeclaration),
+    Module(ModuleDeclaration),
+    Interface(InterfaceDeclaration),
+    Class(ClassDeclaration),
+    Function(FunctionDeclaration),
+    PlatformFunction(PlatformFunctionDeclaration),
+}
+
+#[derive(Debug)]
+pub enum InterfaceLevelDeclaration {
+    Type(TypeDeclaration),
+    Module(ModuleDeclaration),
+    Interface(InterfaceDeclaration),
+    Class(ClassDeclaration),
+    Function(InterfaceFunctionDeclaration),
+    OperatorFunction(InterfaceOperatorFunctionDeclaration),
+}
+
+#[derive(Debug)]
+pub enum ClassLevelDeclaration {
+    Type(TypeDeclaration),
+    Module(ModuleDeclaration),
+    Interface(InterfaceDeclaration),
+    Class(ClassDeclaration),
+    Function(FunctionDeclaration),
+    OperatorFunction(OperatorFunctionDeclaration),
+    PlatformFunction(PlatformFunctionDeclaration),
+    Field(FieldDeclaration),
+}
+
+// Declarations
+
+#[derive(Debug)]
+pub struct TypeDeclaration {
+    pub is_public: bool,
+    pub identifier: Identifier,
+    pub parameters: Option<TypeParameters>,
+    pub where_guards: WhereGuards,
+    pub rhs: TypeUse,
+}
+
+#[derive(Debug)]
+pub struct ModuleDeclaration {
+    pub is_public: bool,
+    pub identifier: Identifier,
+    pub declarations: Vec<ModuleLevelDeclaration>,
+}
+
+#[derive(Debug)]
+pub struct InterfaceDeclaration {
+    pub is_public: bool,
+    pub identifier: Identifier,
+    pub generics: GenericParameters,
+    pub inputs: InputParameters,
+    pub implements: ImplementsList,
+    pub where_guards: WhereGuards,
+    pub declarations: Vec<InterfaceLevelDeclaration>,
+}
+
+#[derive(Debug)]
+pub struct ClassDeclaration {
+    pub is_public: bool,
+    pub identifier: Identifier,
+    pub generics: GenericParameters,
+    pub class_constructor: Option<ClassConstructor>,
+    pub inputs: InputArguments,
+    pub implements: ImplementsList,
+    pub where_guards: WhereGuards,
+    pub declarations: Vec<ClassLevelDeclaration>,
+}
+
+// Function declarations and components
+
+#[derive(Debug)]
+pub enum FunctionModifier {
+    Static,
+    Cons,
+    Mut,
+    Ref,
+    MutRef,
+}
+
+#[derive(Debug)]
+pub enum FunctionBody {
+    EqualsBody(Expression),
+    BlockBody(BlockStatement),
+    AliasBody(Identifier),
+}
+
+#[derive(Debug)]
+pub struct FunctionDeclaration {
+    pub is_public: bool,
+    pub modifier: Option<FunctionModifier>,
+    pub generics: GenericParameters,
+    pub identifier: Identifier,
+    pub parameters: Parameters,
+    pub return_type: Option<ReturnType>,
+    pub body: FunctionBody,
+}
+
+#[derive(Debug)]
+pub struct OperatorFunctionDeclaration {
+    pub is_public: bool,
+    pub modifier: Option<FunctionModifier>,
+    pub generics: GenericParameters,
+    pub operator: Operator,
+    pub parameters: Parameters,
+    pub return_type: Option<ReturnType>,
+    pub body: FunctionBody,
+}
+
+#[derive(Debug)]
+pub struct PlatformFunctionDeclaration {
+    pub is_public: bool,
+    pub modifier: Option<FunctionModifier>,
+    pub generics: GenericParameters,
+    pub identifier: Identifier,
+    pub parameters: Parameters,
+    pub return_type: TypeUse,
+}
+
+#[derive(Debug)]
+pub struct InterfaceFunctionDeclaration {
+    pub modifier: Option<FunctionModifier>,
+    pub generics: GenericParameters,
+    pub identifier: Identifier,
+    pub parameters: Parameters,
+    pub return_type: ReturnType,
+}
+
+#[derive(Debug)]
+pub struct InterfaceOperatorFunctionDeclaration {
+    pub modifier: Option<FunctionModifier>,
+    pub generics: GenericParameters,
+    pub operator: Operator,
+    pub parameters: Parameters,
+    pub return_type: ReturnType,
+}
+
+// Type components
+
+#[derive(Debug)]
+pub enum TypeParameters {
+    Generic(GenericParameters),
+    Tuple(TupleParameters),
+    Function(FunctionTypeParameters),
+}
+
+#[derive(Debug)]
+pub struct TupleParameters(pub Vec<Identifier>);
+
+#[derive(Debug)]
+pub struct FunctionTypeParameters {
+    pub parameters: Parameters,
+    pub return_type: TypeUse,
+}
+
+// Class components
+
+#[derive(Debug)]
+pub struct ClassConstructor(pub Vec<ClassConstructorParameter>);
+
+#[derive(Debug)]
+pub struct ClassConstructorParameter {
+    pub is_field: bool,
+    pub identifier: Identifier,
+    pub declared_type: TypeUse
+}
+
+#[derive(Debug)]
+pub struct FieldDeclaration {
+    pub is_mutable: bool,
+    pub identifier: Identifier,
+    pub declared_type: TypeUse,
+}
+
+// Statements
+
+#[derive(Debug)]
+pub struct BlockStatement(pub Vec<Statement>);
+
 #[derive(Debug)]
 pub enum Statement {
+    BlockStatement(BlockStatement),
     CallStatement(CallExpression),
-    AssignStatement(AssignExpression),
+    VariableDeclarationStatement(VariableDeclarationStatement),
+    AssignStatement(AssignStatement),
+    ReturnStatement(ReturnStatement),
+    IfStatement(IfStatement),
+    IfElseStatement(IfElseStatement),
+    WhileStatement(WhileStatement),
+    ForStatement(ForStatement),
+}
+
+#[derive(Debug)]
+pub struct VariableDeclarationStatement {
+    is_mutable: bool,
+    identifier: Identifier,
+    declared_type: Option<TypeUse>,
+    initializer: Option<Expression>,
+}
+
+#[derive(Debug)]
+pub struct AssignStatement(pub AssignmentExpression);
+
+#[derive(Debug)]
+pub struct ReturnStatement(pub Option<Expression>);
+
+#[derive(Debug)]
+pub struct IfStatement {
+    pub condition: Expression,
+    pub then_branch: BlockStatement,
+}
+
+#[derive(Debug)]
+pub struct IfElseStatement {
+    pub condition: Expression,
+    pub then_branch: BlockStatement,
+    pub else_ifs: ElseIfs,
+    pub else_branch: BlockStatement,
+}
+
+#[derive(Debug)]
+pub struct ElseIfs(pub Vec<IfStatement>);
+
+#[derive(Debug)]
+pub struct WhileStatement {
+    pub condition: Expression,
+    pub body: BlockStatement,
+}
+
+#[derive(Debug)]
+pub struct ForStatement {
+    pub variable: Identifier,
+    pub iterator: Expression,
+    pub body: BlockStatement,
+}
+
+// Expressions
+
+#[derive(Debug)]
+pub enum Expression {
+    Binary(BinaryExpression),
+    Unary(UnaryExpression),
+    Assignment(Box<AssignmentExpression>),
+    Call(CallExpression),
+    Literal(Literal)
+}
+
+#[derive(Debug)]
+pub struct BinaryExpression {
+    pub left: Box<Expression>,
+    pub operator: BinaryOperator,
+    pub right: Box<Expression>,
+}
+
+#[derive(Debug)]
+pub struct UnaryExpression {
+    pub operator: UnaryOperator,
+    pub expression: Box<Expression>,
+}
+
+#[derive(Debug)]
+pub struct AssignmentExpression {
+    identifier: Identifier,
+    expression: Expression,
 }
 
 #[derive(Debug)]
 pub struct CallExpression {
-    receiver: Expression,
-    actuals_list: Vec<Expression>,
-    source_code_location: SourceCodeLocation,
-}
-
-impl CallExpression {
-    pub fn receiver(&self) -> &Expression {
-        &self.receiver
-    }
-
-    pub fn actuals_list(&self) -> &Vec<Expression> {
-        &self.actuals_list
-    }
-
-    pub fn source_code_location(&self) -> &SourceCodeLocation {
-        &self.source_code_location
-    }
+    pub callee: Box<Expression>,
+    pub arguments: CallArguments
 }
 
 #[derive(Debug)]
-pub struct AssignExpression {
-    left: LValue,
-    right: Expression,
-}
+pub struct CallArguments(pub Vec<CallArgument>);
 
 #[derive(Debug)]
-pub enum Expression {
-    CallExpression(Box<CallExpression>),
-    AssignExpression(Box<AssignExpression>),
-    LValue(Box<LValue>),
-    Literal(Box<Literal>),
-}
-
-#[derive(Debug)]
-pub enum LValue {
-    Fqn(Fqn),
-}
+pub struct CallArgument(pub Box<Expression>);
 
 #[derive(Debug)]
 pub enum Literal {
@@ -261,9 +512,3 @@ pub enum Literal {
     StringLiteral(String),
     BooleanLiteral(bool),
 }
-
-#[derive(Debug)]
-pub struct Parameter {
-    identifier: Identifier,
-    declared_type: Option<TypeUse>,
-}
diff --git a/src/ast/unparse.rs b/src/ast/unparse.rs
new file mode 100644
index 0000000..c9922ba
--- /dev/null
+++ b/src/ast/unparse.rs
@@ -0,0 +1,959 @@
+use crate::ast::*;
+
+macro_rules! to_unparse_vec {
+    ( $nodes:expr ) => {
+        $nodes
+            .iter()
+            .map(|node| node as &dyn Unparse)
+            .collect::<Vec<&dyn Unparse>>()
+    };
+}
+
+macro_rules! unparse_contained_declarations {
+    ( $declarations:expr, $buf:expr ) => {
+        if !$declarations.is_empty() {
+            write!($buf, "{{\n")?;
+            unparse_list($buf, "\n\n", &to_unparse_vec!($declarations));
+            write!($buf, "\n}}")?;
+        }
+    };
+}
+
+macro_rules! unparse_ok {
+    () => {
+        Ok(())
+    };
+}
+
+pub trait Unparse {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result;
+}
+
+pub trait ListUnparse: Unparse {
+    fn prefix() -> &'static str {
+        ""
+    }
+
+    fn separator() -> &'static str;
+
+    fn suffix() -> &'static str {
+        ""
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse>;
+}
+
+impl<T: ListUnparse> Unparse for T {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "{}", Self::prefix())?;
+        unparse_list(buf, Self::separator(), &self.inner())?;
+        write!(buf, "{}", Self::suffix())?;
+        unparse_ok!()
+    }
+}
+
+fn unparse_list(
+    buf: &mut dyn std::fmt::Write,
+    sep: &str,
+    items: &[&dyn Unparse],
+) -> std::fmt::Result {
+    for (i, item) in items.iter().enumerate() {
+        item.unparse(buf)?;
+        if i < items.len() - 1 {
+            write!(buf, "{}", sep)?;
+        }
+    }
+    Ok(())
+}
+
+fn unparse_comma_list(buf: &mut dyn std::fmt::Write, items: &[&dyn Unparse]) -> std::fmt::Result {
+    unparse_list(buf, ", ", items)
+}
+
+/* Implementations */
+
+/* Operators */
+
+impl Unparse for Operator {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use Operator::*;
+        match self {
+            Binary(op) => op.unparse(buf),
+            Unary(op) => op.unparse(buf),
+        }
+    }
+}
+
+impl Unparse for BinaryOperator {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use BinaryOperator::*;
+        match self {
+            Or => write!(buf, "||"),
+            And => write!(buf, "&&"),
+            EqualTo => write!(buf, "=="),
+            NotEqualTo => write!(buf, "!="),
+            Greater => write!(buf, ">"),
+            Less => write!(buf, "<"),
+            GreaterEqual => write!(buf, ">="),
+            LessEqual => write!(buf, "<="),
+            Add => write!(buf, "+"),
+            Subtract => write!(buf, "-"),
+            Multiply => write!(buf, "*"),
+            Divide => write!(buf, "/"),
+            Modulo => write!(buf, "%"),
+            LeftShift => write!(buf, "<<"),
+            RightShift => write!(buf, ">>"),
+        }
+    }
+}
+
+impl Unparse for UnaryOperator {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use UnaryOperator::*;
+        match self {
+            Not => write!(buf, "!"),
+            Negative => write!(buf, "-"),
+            PlusPlus => write!(buf, "++"),
+            MinusMinus => write!(buf, "--"),
+            CallOp => write!(buf, "()"),
+            Spread => write!(buf, "..."),
+        }
+    }
+}
+
+/* Names */
+
+impl Unparse for Identifier {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "{}", self.name)
+    }
+}
+
+impl ListUnparse for Fqn {
+    fn separator() -> &'static str {
+        "::"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.identifiers)
+    }
+}
+
+/* Generic Parameters */
+
+impl ListUnparse for GenericParameters {
+    fn prefix() -> &'static str {
+        "<"
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        ">"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for GenericParameter {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.identifier.unparse(buf)
+    }
+}
+
+/* Generic arguments */
+
+impl ListUnparse for GenericArguments {
+    fn prefix() -> &'static str {
+        "<"
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        ">"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for GenericArgument {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.fqn.unparse(buf)
+    }
+}
+
+/* TypeUse and components */
+
+impl Unparse for TypeUse {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.fqn.unparse(buf)?;
+        if let Some(type_arguments) = &self.arguments {
+            type_arguments.unparse(buf)?;
+        }
+        unparse_ok!()
+    }
+}
+
+impl Unparse for TypeArguments {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use TypeArguments::*;
+        match self {
+            Generics(generic_arguments) => generic_arguments.unparse(buf),
+            Tuple(tuple_arguments) => tuple_arguments.unparse(buf),
+            Function(function_type_arguments) => function_type_arguments.unparse(buf),
+        }
+    }
+}
+
+impl ListUnparse for TupleArguments {
+    fn prefix() -> &'static str {
+        "("
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        ")"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for FunctionTypeArguments {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.parameters.unparse(buf)?;
+        write!(buf, " ")?;
+        self.return_type.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+/* Function components */
+
+impl ListUnparse for Parameters {
+    fn prefix() -> &'static str {
+        "("
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        ")"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for Parameter {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.identifier.unparse(buf)?;
+        write!(buf, ": ")?;
+        self.type_use.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for ReturnType {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "-> ")?;
+        self.type_use.unparse(buf)?;
+        if !self.references.is_empty() {
+            self.references.unparse(buf)?;
+        }
+        unparse_ok!()
+    }
+}
+
+impl ListUnparse for References {
+    fn prefix() -> &'static str {
+        "ref "
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for Reference {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.identifier.unparse(buf)
+    }
+}
+
+/* Input parameters and arguments */
+
+impl Unparse for DelegateOrIdentifier {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use DelegateOrIdentifier::*;
+        match self {
+            Delegate => write!(buf, "delegate"),
+            Identifier(identifier) => identifier.unparse(buf),
+        }
+    }
+}
+
+impl ListUnparse for InputParameters {
+    fn prefix() -> &'static str {
+        "|"
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        "|"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl ListUnparse for InputArguments {
+    fn prefix() -> &'static str {
+        "|"
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        "|"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for InputArgument {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.lhs.unparse(buf)?;
+        write!(buf, " = ")?;
+        self.rhs.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+/* Where guards */
+
+impl ListUnparse for WhereGuards {
+    fn prefix() -> &'static str {
+        "where "
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for WhereGuard {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.identifier.unparse(buf)?;
+        write!(buf, " : ")?;
+        self.implements.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+/* Implements */
+
+impl ListUnparse for ImplementsList {
+    fn prefix() -> &'static str {
+        ": "
+    }
+
+    fn separator() -> &'static str {
+        " + "
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+/* Top-level construct */
+
+impl Unparse for CompilationUnit {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if let Some(namespace) = &self.namespace {
+            write!(buf, "ns ")?;
+            namespace.unparse(buf)?;
+            write!(buf, "\n\n")?;
+        }
+        unparse_list(buf, "\n\n", &to_unparse_vec!(self.declarations))?;
+        unparse_ok!()
+    }
+}
+
+/* Declarations allowed in each level */
+
+impl Unparse for ModuleLevelDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use ModuleLevelDeclaration::*;
+        match self {
+            Type(type_declaration) => type_declaration.unparse(buf),
+            Module(module_declaration) => module_declaration.unparse(buf),
+            Interface(interface_declaration) => interface_declaration.unparse(buf),
+            Class(class_declaration) => class_declaration.unparse(buf),
+            Function(function_declaration) => function_declaration.unparse(buf),
+            PlatformFunction(platform_function_declaration) => {
+                platform_function_declaration.unparse(buf)
+            }
+        }
+    }
+}
+
+impl Unparse for InterfaceLevelDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use InterfaceLevelDeclaration::*;
+        match self {
+            Type(type_declaration) => type_declaration.unparse(buf),
+            Module(module_declaration) => module_declaration.unparse(buf),
+            Interface(interface_declaration) => interface_declaration.unparse(buf),
+            Class(class_declaration) => class_declaration.unparse(buf),
+            Function(interface_function_declaration) => interface_function_declaration.unparse(buf),
+            OperatorFunction(interface_operator_function_declaration) => {
+                interface_operator_function_declaration.unparse(buf)
+            }
+        }
+    }
+}
+
+impl Unparse for ClassLevelDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use ClassLevelDeclaration::*;
+        match self {
+            Type(type_declaration) => type_declaration.unparse(buf),
+            Module(module_declaration) => module_declaration.unparse(buf),
+            Interface(interface_declaration) => interface_declaration.unparse(buf),
+            Class(class_declaration) => class_declaration.unparse(buf),
+            Function(function_declaration) => function_declaration.unparse(buf),
+            OperatorFunction(operator_function_declaration) => {
+                operator_function_declaration.unparse(buf)
+            }
+            PlatformFunction(platform_function_declaration) => {
+                platform_function_declaration.unparse(buf)
+            }
+            Field(field_declaration) => field_declaration.unparse(buf),
+        }
+    }
+}
+
+/* Declarations */
+
+impl Unparse for TypeDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_public {
+            write!(buf, "pub ")?;
+        }
+        write!(buf, "type ")?;
+        self.identifier.unparse(buf)?;
+        write!(buf, " ")?;
+        if let Some(type_parameters) = &self.parameters {
+            type_parameters.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        self.where_guards.unparse(buf)?;
+        write!(buf, "= ")?;
+        self.rhs.unparse(buf)?;
+        Ok(())
+    }
+}
+
+impl Unparse for ModuleDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_public {
+            write!(buf, "pub ")?;
+        }
+        write!(buf, "mod ")?;
+        self.identifier.unparse(buf)?;
+        unparse_contained_declarations!(self.declarations, buf);
+        unparse_ok!()
+    }
+}
+
+impl Unparse for InterfaceDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_public {
+            write!(buf, "pub ")?;
+        }
+        write!(buf, "int ")?;
+        self.identifier.unparse(buf)?;
+        if !self.generics.is_empty() {
+            self.generics.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        if !self.inputs.is_empty() {
+            self.inputs.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        if !self.implements.is_empty() {
+            self.implements.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        if !self.where_guards.is_empty() {
+            self.where_guards.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        unparse_contained_declarations!(self.declarations, buf);
+        unparse_ok!()
+    }
+}
+
+impl Unparse for ClassDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_public {
+            write!(buf, "pub ")?;
+        }
+        write!(buf, "class ")?;
+        self.identifier.unparse(buf)?;
+        if !self.generics.is_empty() {
+            self.generics.unparse(buf)?;
+        }
+        if let Some(class_constructor) = &self.class_constructor {
+            class_constructor.unparse(buf)?;
+        }
+        write!(buf, " ")?;
+        if !self.implements.is_empty() {
+            self.implements.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        if !self.inputs.is_empty() {
+            self.inputs.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        if !self.where_guards.is_empty() {
+            self.where_guards.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        unparse_contained_declarations!(self.declarations, buf);
+        unparse_ok!()
+    }
+}
+
+/* Function declarations and components */
+
+impl Unparse for FunctionModifier {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use FunctionModifier::*;
+        match self {
+            Static => write!(buf, "static"),
+            Cons => write!(buf, "cons"),
+            Mut => write!(buf, "mut"),
+            Ref => write!(buf, "ref"),
+            MutRef => write!(buf, "mut ref"),
+        }
+    }
+}
+
+impl Unparse for FunctionBody {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use FunctionBody::*;
+        match self {
+            EqualsBody(expression) => {
+                write!(buf, "= ")?;
+                expression.unparse(buf)
+            }
+            BlockBody(body) => body.unparse(buf),
+            AliasBody(identifier) => {
+                write!(buf, "alias ")?;
+                identifier.unparse(buf)
+            }
+        }
+    }
+}
+
+impl Unparse for FunctionDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_public {
+            write!(buf, "pub ")?;
+        }
+        if let Some(modifier) = &self.modifier {
+            modifier.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        write!(buf, "fn ")?;
+        self.generics.unparse(buf)?;
+        write!(buf, " ")?;
+        self.identifier.unparse(buf)?;
+        self.parameters.unparse(buf)?;
+        write!(buf, " ")?;
+        if let Some(return_type) = &self.return_type {
+            return_type.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        self.body.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for OperatorFunctionDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_public {
+            write!(buf, "pub ")?;
+        }
+        if let Some(modifier) = &self.modifier {
+            modifier.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        self.operator.unparse(buf)?;
+        write!(buf, " ")?;
+        self.parameters.unparse(buf)?;
+        write!(buf, " ")?;
+        if let Some(return_type) = &self.return_type {
+            return_type.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        self.body.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for PlatformFunctionDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_public {
+            write!(buf, "pub ")?;
+        }
+        write!(buf, "platform fn ")?;
+        if !self.generics.is_empty() {
+            self.generics.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        self.identifier.unparse(buf)?;
+        self.parameters.unparse(buf)?;
+        write!(buf, " ")?;
+        self.return_type.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for InterfaceFunctionDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if let Some(modifier) = &self.modifier {
+            modifier.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        if !self.generics.is_empty() {
+            self.parameters.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        self.identifier.unparse(buf)?;
+        self.parameters.unparse(buf)?;
+        write!(buf, " ")?;
+        self.return_type.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for InterfaceOperatorFunctionDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if let Some(modifier) = &self.modifier {
+            modifier.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        write!(buf, "op ")?;
+        if !self.generics.is_empty() {
+            self.generics.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        self.operator.unparse(buf)?;
+        write!(buf, " ")?;
+        self.parameters.unparse(buf)?;
+        write!(buf, " ")?;
+        self.return_type.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+/* Type components */
+
+impl Unparse for TypeParameters {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use TypeParameters::*;
+        match self {
+            Generic(generic_parameters) => generic_parameters.unparse(buf),
+            Tuple(tuple_parameters) => tuple_parameters.unparse(buf),
+            Function(function_type_parameters) => function_type_parameters.unparse(buf),
+        }
+    }
+}
+
+impl ListUnparse for TupleParameters {
+    fn prefix() -> &'static str {
+        "("
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        ")"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for FunctionTypeParameters {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.parameters.unparse(buf)?;
+        write!(buf, " ")?;
+        self.return_type.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+/* Class components */
+
+impl ListUnparse for ClassConstructor {
+    fn prefix() -> &'static str {
+        "("
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        ")"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for ClassConstructorParameter {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_field {
+            write!(buf, "fld ")?;
+        }
+        self.identifier.unparse(buf)?;
+        write!(buf, ": ")?;
+        self.declared_type.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for FieldDeclaration {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        if self.is_mutable {
+            write!(buf, "mut ")?;
+        }
+        self.identifier.unparse(buf)?;
+        write!(buf, ": ")?;
+        self.declared_type.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+/* Statements */
+
+impl ListUnparse for BlockStatement {
+    fn prefix() -> &'static str {
+        "{\n"
+    }
+
+    fn separator() -> &'static str {
+        "\n"
+    }
+
+    fn suffix() -> &'static str {
+        "\n}"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for Statement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        use Statement::*;
+        match self {
+            BlockStatement(statement) => statement.unparse(buf),
+            CallStatement(call_expression) => call_expression.unparse(buf),
+            VariableDeclarationStatement(declaration) => declaration.unparse(buf),
+            AssignStatement(assign_statement) => assign_statement.unparse(buf),
+            ReturnStatement(return_expression) => return_expression.unparse(buf),
+            IfStatement(if_statement) => if_statement.unparse(buf),
+            IfElseStatement(if_else_statement) => if_else_statement.unparse(buf),
+            WhileStatement(while_statement) => while_statement.unparse(buf),
+            ForStatement(for_statement) => for_statement.unparse(buf),
+        }?;
+        write!(buf, "\n")
+    }
+}
+
+impl Unparse for VariableDeclarationStatement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "let ")?;
+        if self.is_mutable {
+            write!(buf, "mut ")?;
+        }
+        self.identifier.unparse(buf)?;
+        if let Some(declared_type) = &self.declared_type {
+            write!(buf, ": ")?;
+            declared_type.unparse(buf)?;
+        }
+        if let Some(initializer) = &self.initializer {
+            write!(buf, " = ")?;
+            initializer.unparse(buf)?;
+        }
+        unparse_ok!()
+    }
+}
+
+impl Unparse for AssignStatement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.0.unparse(buf)
+    }
+}
+
+impl Unparse for ReturnStatement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "return")?;
+        if let Some(expression) = &self.0 {
+            write!(buf, " ")?;
+            expression.unparse(buf)?;
+        }
+        unparse_ok!()
+    }
+}
+
+impl Unparse for IfStatement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "if ")?;
+        self.condition.unparse(buf)?;
+        write!(buf, " {{\n")?;
+        self.then_branch.unparse(buf)?;
+        write!(buf, "\n}}")?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for IfElseStatement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "if ")?;
+        self.condition.unparse(buf)?;
+        write!(buf, " ")?;
+        self.then_branch.unparse(buf)?;
+        write!(buf, " ")?;
+        self.else_ifs.unparse(buf)?;
+        write!(buf, "else ")?;
+        self.else_branch.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for ElseIfs {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        for if_statement in &self.0 {
+            write!(buf, " else ")?;
+            if_statement.unparse(buf)?;
+            write!(buf, " ")?;
+        }
+        unparse_ok!()
+    }
+}
+
+impl Unparse for WhileStatement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "while ")?;
+        self.condition.unparse(buf)?;
+        write!(buf, " ")?;
+        self.body.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for ForStatement {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        write!(buf, "for ")?;
+        self.variable.unparse(buf)?;
+        write!(buf, " in ")?;
+        self.iterator.unparse(buf)?;
+        write!(buf, " ")?;
+        self.body.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+/* Expressions */
+
+impl Unparse for AssignmentExpression {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.identifier.unparse(buf)?;
+        write!(buf, " = ")?;
+        self.expression.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl Unparse for Expression {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        todo!()
+    }
+}
+
+impl Unparse for CallExpression {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.callee.unparse(buf)?;
+        self.arguments.unparse(buf)?;
+        unparse_ok!()
+    }
+}
+
+impl ListUnparse for CallArguments {
+    fn prefix() -> &'static str {
+        "("
+    }
+
+    fn separator() -> &'static str {
+        ", "
+    }
+
+    fn suffix() -> &'static str {
+        ")"
+    }
+
+    fn inner(&self) -> Vec<&dyn Unparse> {
+        to_unparse_vec!(self.0)
+    }
+}
+
+impl Unparse for CallArgument {
+    fn unparse(&self, buf: &mut dyn std::fmt::Write) -> std::fmt::Result {
+        self.0.unparse(buf)
+    }
+}
diff --git a/src/parser/deimos.pest b/src/parser/deimos.pest
index 5a23a88..5bbe47c 100644
--- a/src/parser/deimos.pest
+++ b/src/parser/deimos.pest
@@ -1,78 +1,78 @@
-// Top-level constructs
-CompilationUnit = { SOI ~ Namespace? ~ ModuleLevelDeclaration* ~ EOI }
-Namespace = { "ns" ~ FullyQualifiedName }
+// Keywords
+Ns = { "ns" }
+TypeKw = { "type" }
+Mod = { "mod" }
+Int = { "int" }
+ClassKw = { "class" }
+Platform = { "platform" }
+Pub = { "pub" }
+Fld = { "fld" }
+Impl = { "impl" }
+Mut = { "mut" }
+Cons = { "cons" }
+Static = { "static" }
+Ref = { "ref" }
+Def = { "def" }
+Where = { "where" }
+Infer = { "infer" }
+Void = { "Void" }
+Delegate = { "delegate" }
+Let = { "let" }
+Fn = { "fn" }
+Op = { "op" }
 
-CommonDeclaration = { Interface | Class | Module | Function | OperatorFunction }
-ModuleLevelDeclaration = { Declare? ~ Public? ~ CommonDeclaration }
-InterfaceLevelDeclaration = { CommonDeclaration }
-ClassLevelDeclaration = { Declare? ~ Public? ~ ( CommonDeclaration | ClassMember ) }
-
-// Module
-Module = { "mod" ~ Identifier ~ "{" ~ ModuleLevelDeclaration* ~ "}" }
-
-// Interface
-Interface = { "int" ~ Identifier ~ GenericParameters? ~  ExtendsList? ~ ( "{" ~ InterfaceLevelDeclaration* ~ "}" )? }
-
-// Class
-Class = { "class" ~ Identifier ~ GenericParameters? ~ ClassConstructor? ~ ExtendsList? ~ ( "{" ~ ClassLevelDeclaration* ~ "}" )? }
-ClassMember = { Field? ~ Identifier ~ TypeAnnotation? }
-
-// Class Constructor
-ClassConstructor = { "(" ~ ClassMemberList? ~ ")" }
-ClassMemberList = { ClassMember ~ ( "," ~ ClassMember )* }
-
-// Various Keywords
-Declare = { "decl" }
-Public = { "pub" }
-Field = { "fld" }
-Implementation = { "impl" }
-Mutable = { "mut" }
-Consume = { "cons" }
-Reference = { "ref" }
-Define = { "def" }
-
-// Fqn and identifier
-FullyQualifiedName = { Identifier ~ ( "::" ~ Identifier )* }
-
-Identifier = @{ IdentifierStartChar ~ IdentifierChar* }
-IdentifierStartChar = { 'a'..'z' | 'A'..'Z' | "_" }
-IdentifierChar = { 'a'..'z' | 'A'..'Z' | '0'..'9' | "_" }
-
-// Type constructs
-ExtendsList = { ":" ~ TypeUse ~ ( "+" ~ TypeUse )* }
-TypeAnnotation = { ":" ~ TypeUse }
-TypeUse = { FullyQualifiedName ~ GenericArguments? }
-
-// Generic arguments given to a TypeUse or function calls
-GenericArguments = { "<" ~ FullyQualifiedName ~ ( "," ~ FullyQualifiedName )* ~ ">" }
-
-// Generic parameters (for when types are declared)
-GenericParameters = { "<" ~ Identifier ~ ( "," ~ Identifier )* ~ ">" }
-
-// Function
-Function = { ( Implementation | Define )?
-    ~ ( Consume | Mutable )?
-    ~ Reference?
-    ~ "fn"
-    ~ GenericParameters?
-    ~ Identifier
-    ~ "(" ~ Parameters? ~ ")"
-    ~ ReturnType?
-    ~ ( FunctionAlias | FunctionEqualsBody | BlockStatement )?
+// Keywords as a rule (for preventing identifiers with keywords, etc.)
+Keyword = {
+      Ns
+    | TypeKw
+    | Mod
+    | Int
+    | ClassKw
+    | Platform
+    | Pub
+    | Fld
+    | Impl
+    | Mut
+    | Cons
+    | Static
+    | Ref
+    | Def
+    | Where
+    | Infer
+    | Void
+    | Delegate
+    | Let
+    | Fn
+    | Op
 }
-ReturnType = { "->" ~ Reference? ~ TypeUse }
-FunctionAlias = { "alias" ~ FullyQualifiedName }
 
-OperatorFunction = { ( Implementation | Define )?
-    ~ ( Consume | Mutable )?
-    ~ Reference?
-    ~ "op"
-    ~ Operator
-    ~ "(" ~ Parameters? ~ ")"
-    ~ ReturnType?
-    ~ ( FunctionAlias | FunctionEqualsBody | BlockStatement )?
-}
-Operator = { Or
+// Symbols
+Ellipsis = { "..." }
+Underscore = { "_" }
+
+// Operators
+Or = { "||" }
+And = { "&&" }
+EqualTo = { "==" }
+NotEqualTo = { "!=" }
+Greater = { ">" }
+Less = { "<" }
+GreaterEqual = { ">=" }
+LessEqual = { "<=" }
+Add = { "+" }
+Subtract = { "-" }
+Multiply = { "*" }
+Divide = { "/" }
+Modulo = { "%" }
+Not = { "!" }
+Negative = { "-" }
+PlusPlus = { "++" }
+MinusMinus = { "--" }
+CallOp = { "()" }
+Spread = { Ellipsis }
+
+Operator = {
+      Or
     | And
     | EqualTo
     | NotEqualTo
@@ -85,93 +85,691 @@ Operator = { Or
     | Multiply
     | Divide
     | Modulo
+    | Not
+    | Negative
+    | PlusPlus
+    | MinusMinus
     | CallOp
+    | Spread
 }
 
-CallOp = { "()" }
+// Commonly shared constructs
 
-Parameters = { Parameter ~ ( "," ~ Parameter )* }
-Parameter = { Identifier ~ TypeAnnotation? }
+FullyQualifiedName = {
+      Identifier
+    ~ ( "::" ~ Identifier )*
+}
 
-FunctionEqualsBody = { "=" ~ Expression }
+Identifier = @{
+      ( Keyword ~ IdentifierChar | !Keyword ~ IdentifierStartChar )
+    ~ IdentifierChar*
+}
+
+IdentifierStartChar = {
+      'a'..'z'
+    | 'A'..'Z'
+    | "_"
+}
+
+IdentifierChar = {
+      'a'..'z'
+    | 'A'..'Z'
+    | '0'..'9'
+    | "_"
+}
+
+// In general:
+// Arguments = usage
+// Parameters = declaration
+
+TypeUse = {
+      FullyQualifiedName
+    ~ (
+          GenericArguments ~ InputArguments?
+        | TupleGenericArguments
+        | FunctionGenericArguments ~ FunctionInputArguments?
+        | InputArguments
+      )?
+}
+
+GenericArguments = {
+      "<"
+    ~ FullyQualifiedName
+    ~ ( "," ~ FullyQualifiedName )*
+    ~ ">"
+}
+
+InputArguments = {
+      "|"
+    ~ (
+          InputArgument
+        ~ ( "," ~ InputArgument )*
+      )?
+    ~ "|"
+}
+
+InputArgument = {
+      Identifier
+    ~ ( "=" ~ Identifier )
+}
+
+TupleGenericArguments = {
+      "("
+    ~ (
+        FullyQualifiedName
+        ~ ( "," ~ FullyQualifiedName )*
+      )?
+    ~ ")"
+}
+
+FunctionGenericArguments = {
+      TupleGenericArguments
+    ~ ReturnTypeGenericArgument
+    ~ FunctionInputArguments?
+}
+
+ReturnTypeGenericArgument = {
+      "->"
+    ~ ( Void | FullyQualifiedName )
+    ~ RefList?
+}
+
+RefList = {
+      Ref
+    ~ Identifier
+    ~ ( "," ~ Identifier )*
+}
+
+FunctionInputArguments = {
+      "|"
+    ~ (
+          FunctionInputArgument
+        ~ ( "," ~ FunctionInputArgument )*
+      )?
+    ~ "|"
+}
+
+FunctionInputArgument = {
+      ( Delegate | Identifier )
+    ~ ( "=" ~ Identifier )
+}
+
+// Generic Parameters
+
+GenericParameters = {
+      "<"
+    ~ Identifier
+    ~ ( "," ~ Identifier )*
+    ~ ">"
+}
+
+InputParameters = {
+      "|"
+    ~ InputParameter
+    ~ ( "," ~ InputParameter )*
+    ~ "|"
+}
+
+InputParameter = {
+      Identifier
+    ~ ":"
+    ~ TypeUse
+}
+
+TupleGenericParameters = {
+      "("
+    ~ (
+          Identifier
+        ~ ( "," ~ Identifier )*
+      )?
+    ~ ")"
+}
+
+FunctionGenericParameters = {
+      TupleGenericParameters
+    ~ FunctionGenericParameterReturnType
+}
+
+FunctionGenericParameterReturnType = {
+      "->"
+    ~ ( Void | Identifier )
+    ~ RefList?
+}
+
+FunctionInputParameters = {
+      "|"
+    ~ FunctionInputParameter
+    ~ ( "," ~ FunctionInputParameter )*
+    ~ "|"
+}
+
+FunctionInputParameter = {
+      ( Delegate | Identifier )
+    ~ ":"
+    ~ TypeUse
+}
+
+ImplementsList = {
+      ":"
+    ~ TypeUse
+    ~ ( "+" ~ TypeUse )
+}
+
+WhereGuards = {
+      Where
+    ~ WhereGuard
+    ~ ( "," ~ WhereGuard )*
+}
+
+WhereGuard = {
+      Identifier
+    ~ ImplementsList
+}
+
+// Top-level constructs
+
+CompilationUnit = {
+      SOI
+    ~ Namespace?
+    ~ ModuleLevelDeclaration*
+    ~ EOI
+}
+
+Namespace = {
+      Ns
+    ~ FullyQualifiedName
+}
+
+// Organizational declarations
+
+ModuleLevelDeclaration = {
+      Type
+    | Module
+    | Interface
+    | Class
+    | FunctionDefinition
+    | PlatformFunction
+}
+
+InterfaceLevelDeclaration = {
+      Type
+    | Module
+    | Interface
+    | Class
+    | InterfaceFunction
+    | InterfaceDefaultFunction
+    | InterfaceOperatorFunction
+    | InterfaceDefaultOperatorFunction
+}
+
+ClassLevelDeclaration = {
+      Type
+    | Module
+    | Interface
+    | Class
+    | FunctionDefinition
+    | OperatorFunctionDefinition
+    | PlatformFunction
+    | Field
+}
+
+// Main organizational constructs
+
+Type = {
+      Pub?
+    ~ TypeKw
+    ~ Identifier
+    ~ GenericParameters?
+    ~ TypeWhereGuards?
+    ~ "="
+    ~ TypeUse
+}
+
+Module = {
+      Pub?
+    ~ Mod
+    ~ Identifier
+    ~ "{" ~ ModuleLevelDeclaration* ~ "}"
+}
+
+Interface = {
+      Pub?
+    ~ Int
+    ~ Identifier
+    ~ InterfaceGenericParametersAndInputs?
+    ~ ImplementsList?
+    ~ WhereGuards?
+    ~ ( "{" ~ InterfaceLevelDeclaration* ~ "}" )?
+}
+
+Class = {
+      Pub?
+    ~ ClassKw
+    ~ Identifier
+    ~ GenericParameters?
+    ~ ClassConstructor?
+    ~ ImplementsList?
+    ~ InputArguments?
+    ~ WhereGuards?
+    ~ ( "{" ~ ClassLevelDeclaration* ~ "}" )?
+}
+
+// Type
+
+TypeWhereGuards = {
+      Where
+    ~ TypeWhereGuard
+    ~ ( "," ~ TypeWhereGuard )*
+}
+
+TypeWhereGuard = {
+      Identifier
+    ~ ":"
+    ~ TypeTypeUse
+    ~ ( "+" ~ TypeTypeUse )*
+}
+
+TypeTypeUse = {
+      FullyQualifiedName
+    ~ TypeTypeArguments?
+}
+
+TypeTypeArguments = {
+      TypeGenericArguments
+    | TypeGenericFunctionArguments
+    | TypeGenericTupleArguments
+}
+
+TypeGenericArguments = {
+      "<"
+    ~ TypeGenericArgument
+    ~ ( "," ~ TypeGenericArgument )*
+    ~ ">"
+}
+
+TypeGenericArgument = {
+      Underscore
+    | FullyQualifiedName
+    | ( Infer ~ Identifier )
+}
+
+TypeGenericTupleArguments = {
+      "("
+    ~ (
+          TypeGenericTupleArgument
+        ~ ( "," ~ TypeGenericTupleArgument )*
+      )?
+    ~ ")"
+}
+
+TypeGenericTupleArgument = {
+      Underscore
+    | FullyQualifiedName
+    | ( Infer ~ Identifier )
+    | ( Ellipsis ~ Underscore )
+    | ( Ellipsis ~ Infer ~ Identifier )
+}
+
+TypeGenericFunctionArguments = {
+      TypeGenericTupleArguments
+    ~ TypeGenericArguments?
+    ~ TypeFunctionReturnType
+}
+
+TypeFunctionReturnType = {
+      "->"
+    ~ ( Void | FullyQualifiedName )
+    ~ RefList?
+}
+
+// Interface
+
+InterfaceGenericParametersAndInputs = {
+      GenericParameters ~ InputParameters?
+    | TupleGenericParameters
+    | FunctionGenericParameters ~ FunctionInputParameters?
+    | InputParameters
+}
+
+InterfaceFunction = {
+      (
+          Static
+        | Cons
+        | ( Mut ~ Ref? )
+      )?
+    ~ Fn
+    ~ GenericParameters?
+    ~ Identifier
+    ~ Parameters
+    ~ ReturnType
+    ~ WhereGuards?
+}
+
+InterfaceDefaultFunction = {
+      Def
+    ~ (
+          Static
+        | Cons
+        | ( Mut ~ Ref? )
+      )?
+    ~ Fn
+    ~ GenericParameters?
+    ~ Identifier
+    ~ Parameters
+    ~ ReturnType
+    ~ WhereGuards?
+    ~ FunctionBody
+}
+
+InterfaceOperatorFunction = {
+      (
+          Cons
+        | ( Mut ~ Ref? )
+      )?
+    ~ Op
+    ~ Operator
+    ~ Parameters
+    ~ ReturnType
+    ~ RefList?
+    ~ WhereGuards? // TODO: decide if we want this for interface op functions
+}
+
+InterfaceDefaultOperatorFunction = {
+      Def
+    ~ (
+          Cons
+        | ( Mut ~ Ref? )
+      )?
+    ~ Op
+    ~ Operator
+    ~ Parameters
+    ~ ReturnType
+    ~ RefList?
+    ~ WhereGuards?
+    ~ FunctionBody
+}
+
+// Class constructs
+
+ClassConstructor = {
+      "("
+    ~ DataMember
+    ~ ( "," ~ DataMember )*
+    ~ ")"
+}
+
+DataMember = {
+      Property
+    | Field
+}
+
+Property = {
+      Mut?
+    ~ Identifier
+    ~ ":"
+    ~ TypeUse
+}
+
+Field = {
+      Mut?
+    ~ Fld
+    ~ Identifier
+    ~ ":"
+    ~ TypeUse
+}
+
+// Function constructs
+FunctionModifier = {
+      Static
+    | Cons
+    | Mut? Ref?
+}
+
+FunctionDefinition = {
+      Pub?
+    ~ FunctionModifier
+    ~ Fn
+    ~ GenericParameters?
+    ~ Identifier
+    ~ Parameters
+    ~ ReturnType?
+    ~ FunctionBody
+}
+
+OperatorFunctionDefinition = {
+      Pub?
+    ~ FunctionModifier
+    ~ Op
+    ~ Operator
+    ~ Parameters
+    ~ ReturnType?
+    ~ FunctionBody
+}
+
+PlatformFunction = {
+      Pub?
+    ~ FunctionModifier
+    ~ Platform
+    ~ Fn
+    ~ GenericParameters
+    ~ Identifier
+    ~ Parameters
+    ~ ReturnType
+}
+
+Parameters = {
+      "("
+    ~ (
+          Parameter
+        ~ ( "," ~ Parameter )*
+      )?
+    ~ ")"
+}
+
+Parameter = {
+      Identifier
+    ~ ":"
+    ~ TypeUse
+}
+
+ReturnType = {
+      "->"
+    ~ ( Void | TypeUse )
+    ~ RefList?
+}
+
+FunctionBody = {
+      FunctionEqualsBody
+    | FunctionBlockBody
+    | FunctionAliasBody
+}
+
+FunctionEqualsBody = {
+      "="
+    ~ Expression
+}
+
+FunctionBlockBody = {
+      "{"
+    ~ Statement*
+    ~ "}"
+}
+
+FunctionAliasBody = {
+      "alias"
+    ~ Identifier
+}
 
 // Statements
-BlockStatement = { "{" ~ Statement* ~ "}" }
-Statement = { VariableDeclaration | CallExpression | AssignmentExpression }
 
-VariableDeclaration = { "let" ~ Mutable? ~ Identifier ~ TypeAnnotation? ~ ( "=" ~ Expression )? }
+BlockStatement = {
+      "{"
+    ~ Statement*
+    ~ "}"
+}
+
+Statement = {
+      BlockStatement
+    | VariableDeclaration
+    | AssignmentExpression
+}
+
+VariableDeclaration = {
+      Let
+    ~ Mut?
+    ~ Identifier
+    ~ ( ":" ~ TypeUse )?
+    ~ ( "=" ~ Expression )?
+}
 
 // Expressions
+
 Expression = { OrExpression }
 
-OrExpression = { AndExpression ~ ( Or ~ AndExpression )* }
-AndExpression = { EqualityExpression ~ ( And ~ EqualityExpression )* }
-Or = { "||" }
-And = { "&&" }
+OrExpression = {
+      AndExpression
+    ~ ( Or ~ Expression )*
+}
 
-EqualityExpression = { ComparisonExpression ~ ( ( EqualTo | NotEqualTo ) ~ ComparisonExpression )* }
-EqualTo = { "==" }
-NotEqualTo = { "!=" }
+AndExpression = {
+      EqualityExpression
+    ~ ( And ~ Expression )*
+}
 
-ComparisonExpression = { AdditiveExpression ~ ( ( Greater | Less | GreaterEqual | LessEqual ) ~ AdditiveExpression )* }
-Greater = { ">" }
-Less = { "<" }
-GreaterEqual = { ">=" }
-LessEqual = { "<=" }
+EqualityExpression = {
+      ComparisonExpression
+    ~ (
+          ( EqualTo | NotEqualTo )
+        ~ Expression
+      )*
+}
 
-AdditiveExpression = { MultiplicativeExpression ~ ( ( Add | Subtract ) ~ MultiplicativeExpression )* }
-Add = { "+" }
-Subtract = { "-" }
+ComparisonExpression = {
+      AdditiveExpression
+    ~ (
+          ( Greater | Less | GreaterEqual | LessEqual )
+        ~ Expression
+      )*
+}
 
-MultiplicativeExpression = { UnaryExpression ~ ( ( Multiply | Divide | Modulo ) ~ UnaryExpression )* }
-Multiply = { "*" }
-Divide = { "/" }
-Modulo = { "%" }
+AdditiveExpression = {
+      MultiplicativeExpression
+    ~ (
+          ( Add | Subtract )
+        ~ Expression
+      )*
+}
 
-UnaryExpression = { ( Not | Negative )* ~ PrimaryExpression ~ ( Call | ( PlusPlus | MinusMinus ) )* }
-Not = { "!" }
-Negative = { "-" }
-PlusPlus = { "++" }
-MinusMinus = { "--" }
+MultiplicativeExpression = {
+      SpreadExpression
+    ~ (
+          ( Multiply | Divide | Modulo )
+        ~ Expression
+      )*
+}
 
-PrimaryExpression = { Literal | ObjectAccess | ParenthesizedExpression }
-ParenthesizedExpression = { "(" ~ Expression ~ ")" }
+SpreadExpression = {
+      UnaryExpression
+    ~ Spread
+    ~ Expression
+}
 
+UnaryExpression = {
+      ( Not | Negative )*
+    ~ PrimaryExpression
+    ~ ( ( NoParenthesesCall | ParenthesesCall )+ | ( PlusPlus | MinusMinus ) )?
+}
 
-// Call
-CallExpression = { PrimaryExpression ~ Call+ }
-Call = { GenericArguments? ~ CallArguments }
-ExpressionList = { Expression ~ ( "," ~ Expression )* }
-CallArguments = {
-    ( "(" ~ ExpressionList? ~ ")" )
-    | ExpressionList
+PrimaryExpression = {
+      Literal
+    | ObjectAccess
+    | ParenthesizedExpression
+}
+
+ParenthesizedExpression = {
+      "("
+    ~ Expression
+    ~ ")"
+}
+
+// Calls
+
+ParenthesesCall = {
+      TurboFish?
+    ~ "("
+    ~ ExpressionList?
+    ~ ")"
+}
+
+NoParenthesesCall = {
+      TurboFish?
+    ~ ExpressionList
+}
+
+TurboFish = {
+      "::"
+    ~ GenericArguments
+}
+
+ExpressionList = {
+      Expression
+    ~ ( "," ~ Expression )*
 }
 
 // Assignment
-AssignmentExpression = { ObjectAccess ~ "=" ~ Expression }
+AssignmentExpression = {
+      ObjectAccess
+    ~ "="
+    ~ Expression
+}
 
 // Object
-ObjectAccess = { FullyQualifiedName ~ ( "." ~ Identifier )* }
+ObjectAccess = {
+      FullyQualifiedName
+    ~ ( "." ~ Identifier )*
+}
 
 // Literals
-Literal = { NumberLiteral | StringLiteral | BooleanLiteral | NullLiteral }
+Literal = {
+      NumberLiteral
+    | StringLiteral
+    | BooleanLiteral
+}
 
-NumberLiteral = { LongLiteral | IntLiteral }
+NumberLiteral = {
+      LongLiteral
+    | IntLiteral
+    | DoubleLiteral
+}
 
 IntLiteral = { NumberBase }
+
 LongLiteral = ${ NumberBase ~ "L" }
 
-NumberBase = { DecimalBase | BinaryBase | HexadecimalBase }
+DoubleLiteral = ${ DecimalBase ~ "." ~ Digit+ }
+
+NumberBase = {
+      DecimalBase
+    | BinaryBase
+    | HexadecimalBase
+}
 
 DecimalBase = @{ DecimalStartDigit ~ Digit* }
+
 BinaryBase = @{ "0b" ~ Digit* }
+
 DecimalStartDigit = { '1'..'9' }
+
 Digit = { '0'..'9'+ }
+
 HexadecimalBase = @{ "0x" ~ HexadecimalDigit+ }
+
 HexadecimalDigit = { '0'..'9' | 'a'..'f' }
 
 StringLiteral = ${ "\"" ~ StringInner ~ "\"" }
+
 StringInner = @{ StringChar* }
+
 StringChar = {
     !( "\"" | "\\" ) ~ ANY
     | "\\" ~ ( "\"" | "\\" | "/" | "b" | "f" | "n" | "r" | "t" )
@@ -180,6 +778,4 @@ StringChar = {
 
 BooleanLiteral = { "true" | "false" }
 
-NullLiteral = { "null" }
-
 WHITESPACE = _{ " " | "\t" | "\n" | "\r" }