diff --git a/src/main/wacc/Frontend/microWacc.scala b/src/main/wacc/Frontend/microWacc.scala
new file mode 100644
index 0000000..1faf3a8
--- /dev/null
+++ b/src/main/wacc/Frontend/microWacc.scala
@@ -0,0 +1,67 @@
+package wacc
+
+import cats.data.NonEmptyList
+
+object microWacc {
+  import wacc.types._
+
+  sealed trait CallTarget
+  sealed trait Expr(val ty: SemType)
+  sealed trait LValue
+
+  // Atomic expressions
+  case class IntLiter(v: Int) extends Expr(KnownType.Int)
+  case class BoolLiter(v: Boolean) extends Expr(KnownType.Bool)
+  case class CharLiter(v: Char) extends Expr(KnownType.Char)
+  case class ArrayLiter(elems: List[Expr])(ty: SemType) extends Expr(ty)
+  case class Ident(name: String)(identTy: SemType) extends Expr(identTy) with CallTarget with LValue
+  case class ArrayElem(name: Ident, indices: NonEmptyList[Expr])(ty: SemType)
+      extends Expr(ty)
+      with LValue
+
+  // Operators
+  case class UnaryOp(x: Expr, op: UnaryOperator)(ty: SemType) extends Expr(ty)
+  enum UnaryOperator {
+    case Negate
+    case Not
+    case Len
+    case Ord
+    case Chr
+  }
+  case class BinaryOp(x: Expr, y: Expr, op: BinaryOperator)(ty: SemType) extends Expr(ty)
+  enum BinaryOperator {
+    case Add
+    case Sub
+    case Mul
+    case Div
+    case Mod
+    case Greater
+    case GreaterEq
+    case Less
+    case LessEq
+    case Eq
+    case Neq
+    case And
+    case Or
+  }
+
+  // Statements
+  sealed trait Stmt
+
+  enum Builtin extends CallTarget {
+    case Read
+    case Free
+    case Exit
+    case Print
+  }
+
+  case class Assign(lhs: LValue, rhs: Expr) extends Stmt
+  case class If(cond: Expr, thenBranch: List[Stmt], elseBranch: List[Stmt]) extends Stmt
+  case class While(cond: Expr, body: List[Stmt]) extends Stmt
+  case class Call(target: CallTarget, args: List[Expr]) extends Stmt
+  case class Return(expr: Expr) extends Stmt
+
+  // Program
+  case class FuncDecl(name: Ident, params: List[Ident], body: List[Stmt])
+  case class Program(funcs: List[FuncDecl], stmts: List[Stmt])
+}