type value =
  | Int of int
  | Closure of { code : int; env : value list }
  | Continuation of continuation
  | Bool of bool

and continuation =
  | Halt
  | Return_to of continuation
  | Apply_to of { func : value; cont : continuation }
  | Eval_to of { expr : t; cont : continuation }
  | Pop_to of { n : int; cont : continuation }
  | Exception_to of { handler : continuation; cont : continuation }

and t =
  | PUSH of value
  | POP
  | DUP
  | SWAP
  | OVER
  | ROT
  | ADD
  | SUB
  | MUL
  | DIV
  | MOD
  | EQ
  | NE
  | LT
  | LE
  | GT
  | GE
  | AND
  | OR
  | NOT
  | NEG
  | JMP of int
  | JMP_IF of int
  | JMP_IF_NOT of int
  | CALL
  | RET
  | MK_CLOSURE of int
  | LOAD of int
  | STORE of int
  | PUSH_ENV
  | POP_ENV
  | HALT
  | TRY of int
  | RAISE
  | RERAISE

let show_value = function
  | Int n -> Printf.sprintf "Int(%d)" n
  | Bool b -> Printf.sprintf "Bool(%b)" b
  | Closure { code; env } -> Printf.sprintf "Closure(code=%d, env_len=%d)" code (List.length env)
  | Continuation _ -> "Continuation"

let show_continuation = function
  | Halt -> "Halt"
  | Return_to _ -> "Return_to"
  | Apply_to _ -> "Apply_to"
  | Eval_to _ -> "Eval_to"
  | Pop_to _ -> "Pop_to"
  | Exception_to _ -> "Exception_to"

let show = function
  | PUSH v -> Printf.sprintf "PUSH %s" (show_value v)
  | POP -> "POP"
  | DUP -> "DUP"
  | SWAP -> "SWAP"
  | OVER -> "OVER"
  | ROT -> "ROT"
  | ADD -> "ADD"
  | SUB -> "SUB"
  | MUL -> "MUL"
  | DIV -> "DIV"
  | MOD -> "MOD"
  | EQ -> "EQ"
  | NE -> "NE"
  | LT -> "LT"
  | LE -> "LE"
  | GT -> "GT"
  | GE -> "GE"
  | AND -> "AND"
  | OR -> "OR"
  | NOT -> "NOT"
  | NEG -> "NEG"
  | JMP offset -> Printf.sprintf "JMP %d" offset
  | JMP_IF offset -> Printf.sprintf "JMP_IF %d" offset
  | JMP_IF_NOT offset -> Printf.sprintf "JMP_IF_NOT %d" offset
  | CALL -> "CALL"
  | RET -> "RET"
  | MK_CLOSURE code -> Printf.sprintf "MK_CLOSURE %d" code
  | LOAD idx -> Printf.sprintf "LOAD %d" idx
  | STORE idx -> Printf.sprintf "STORE %d" idx
  | PUSH_ENV -> "PUSH_ENV"
  | POP_ENV -> "POP_ENV"
  | HALT -> "HALT"
  | TRY offset -> Printf.sprintf "TRY %d" offset
  | RAISE -> "RAISE"
  | RERAISE -> "RERAISE"

let int_of_value = function
  | Int n -> Some n
  | Bool true -> Some 1
  | Bool false -> Some 0
  | _ -> None

let bool_of_value = function
  | Bool b -> Some b
  | Int 0 -> Some false
  | Int n -> Some (n <> 0)
  | _ -> None