import TsmLean.Core.Syntax

namespace TsmLean.Compile.Source

/-! # Source language for compilation (v0.4).

Integer/bool literals + arithmetic. The compile function takes an
offset (infrastructure for future control-flow constructs that
require absolute jump addresses). For the constructs in v0.4, the
offset doesn't change the compile output — it's just threaded. -/

inductive Expr where
  | intLit  : Int  → Expr
  | boolLit : Bool → Expr
  | add     : Expr → Expr → Expr
  | sub     : Expr → Expr → Expr
  | mul     : Expr → Expr → Expr
  deriving Repr, Inhabited

abbrev Value := TsmLean.Core.Value

inductive Eval : Expr → Value → Prop where
  | intLit  (n : Int)  : Eval (.intLit n)  (.vInt n)
  | boolLit (b : Bool) : Eval (.boolLit b) (.vBool b)
  | add {e1 e2 a b}
        (h1 : Eval e1 (.vInt a)) (h2 : Eval e2 (.vInt b)) :
      Eval (.add e1 e2) (.vInt (a + b))
  | sub {e1 e2 a b}
        (h1 : Eval e1 (.vInt a)) (h2 : Eval e2 (.vInt b)) :
      Eval (.sub e1 e2) (.vInt (a - b))
  | mul {e1 e2 a b}
        (h1 : Eval e1 (.vInt a)) (h2 : Eval e2 (.vInt b)) :
      Eval (.mul e1 e2) (.vInt (a * b))

end TsmLean.Compile.Source