ligo/src/operators/operators.ml

open Trace

(*
  This file is used throughout the pipeline. Its idea is to add a unique place
  that you have to modify when you add a new operator/constant to the language.

  This file mirrors the LIGO pipeline, starting with Simplify, then Typer and
  ending with Compiler. Usually, when adding a new operator, you'll have to add
  a new constructor at all those places.
*)

module Simplify = struct

  (*
    Each front-end has its owns constants.

    Constants are special names that have their own case in the AST. E_constant
    for regular constants, and T_constant for type constants. Both types are
    defined in `Ast_simplified/types.ml`.
    For instance, "2 + 2" in Pascaligo is translated to `E_constant ("ADD" , [
      E_literal (Literal_int 2) ;
      E_literal (Literal_int 2) ;
    ])`.

    They are used to represent what can't expressed in the languages:
    - Primitives. Like "int", "string", "unit" for types. Or "+" for values.
    - Tezos specific stuff. Like "operation" for types. Or "source" for values.
    - What can't be represented in the language yet. Like "list" or "List.fold".

    Each constant is expressed as a pair:
    - The left-hand-side is the reserved name in the given front-end.
    - The right-hand-side is the name that will be used in the AST.
  *)

  let type_constants = [
    ("unit" , "unit") ;
    ("string" , "string") ;
    ("bytes" , "bytes") ;
    ("nat" , "nat") ;
    ("int" , "int") ;
    ("tez" , "tez") ;
    ("bool" , "bool") ;
    ("operation" , "operation") ;
    ("address" , "address") ;
    ("contract" , "contract") ;
    ("list" , "list") ;
    ("option" , "option") ;
    ("set" , "set") ;
    ("map" , "map") ;
    ("big_map" , "big_map") ;
  ]

  module Pascaligo = struct

    let constants = [
      ("get_force" , "MAP_GET_FORCE") ;
      ("transaction" , "CALL") ;
      ("get_contract" , "CONTRACT") ;
      ("size" , "SIZE") ;
      ("int" , "INT") ;
      ("abs" , "ABS") ;
      ("amount" , "AMOUNT") ;
      ("unit" , "UNIT") ;
      ("source" , "SOURCE") ;
      ("failwith" , "FAILWITH") ;
    ]

    let type_constants = type_constants
  end

  module Camligo = struct
    let constants = [
      ("Bytes.pack" , "PACK") ;
      ("Crypto.hash" , "HASH") ;
      ("Operation.transaction" , "CALL") ;
      ("Operation.get_contract" , "GET_CONTRACT") ;
      ("sender" , "SENDER") ;
      ("unit" , "UNIT") ;
      ("source" , "SOURCE") ;
    ]

    let type_constants = type_constants
  end

  module Ligodity = struct
    include Pascaligo
  end

end

module Typer = struct
  (*
    Each constant has its own type.

    LIGO's type-system is currently too
    weak to express the constant's type. For instance:
    - "ADD" has a special kind of type of polymorphism. If "ADD" gets two `int`s,
      it will return an `int`. If it gets two `nat`s, it will return a `nat`.
      Regular polymorphism wouldn't work because "ADD" only accepts `int`s or
      `nat`s.
    - "NONE" (from Some/None) requires an annotation.

    Instead of a LIGO type, constant types are representend as functions. These
    functions take as parameters:
    - The list of types of the arguments of the constants. When typing `2 + 2`,
      the types might be `[ int ; int ]`.
    - The expected type of the whole expression. It is optional. When typing
      `[] : list(operation)`, it will be `Some ( list (operation) )`. When
      typing `2 + 2` (with no additional context), it will be `None`.
    The output is the type of the whole expression. An error is returned through
    the Trace monad if it doesn't type-check (`"toto" + 42`).

    Various helpers are defined and explaines in `Helpers.Typer`.
  *)

  open Helpers.Typer
  open Ast_typed

  let none = typer_0 "NONE" @@ fun tv_opt ->
    match tv_opt with
    | None -> simple_fail "untyped NONE"
    | Some t -> ok t

  let sub = typer_2 "SUB" @@ fun a b ->
    let%bind () =
      trace_strong (simple_error "Types a and b aren't numbers") @@
      Assert.assert_true @@
      List.exists (eq_2 (a , b)) [
        t_int () ;
        t_nat () ;
      ] in
    ok @@ t_int ()

  let some = typer_1 "SOME" @@ fun a -> ok @@ t_option a ()

  let map_remove : typer = typer_2 "MAP_REMOVE" @@ fun k m ->
    let%bind (src , _) = get_t_map m in
    let%bind () = assert_type_value_eq (src , k) in
    ok m

  let map_update : typer = typer_3 "MAP_UPDATE" @@ fun k v m ->
    let%bind (src, dst) = get_t_map m in
    let%bind () = assert_type_value_eq (src, k) in
    let%bind () = assert_type_value_eq (dst, v) in
    ok m

  let size = typer_1 "SIZE" @@ fun t ->
    let%bind () =
      Assert.assert_true @@
      (is_t_map t || is_t_list t) in
    ok @@ t_nat ()

  let failwith_ = typer_1 "FAILWITH" @@ fun t ->
    let%bind () =
      Assert.assert_true @@
      (is_t_string t) in
    ok @@ t_unit ()

  let get_force = typer_2 "MAP_GET_FORCE" @@ fun i m ->
    let%bind (src, dst) = get_t_map m in
    let%bind _ = assert_type_value_eq (src, i) in
    ok dst

  let int : typer = typer_1 "INT" @@ fun t ->
    let%bind () = assert_t_nat t in
    ok @@ t_int ()

  let bytes_pack : typer = typer_1 "PACK" @@ fun _t ->
    ok @@ t_bytes ()

  let bytes_unpack = typer_1_opt "UNPACK" @@ fun input output_opt ->
    let%bind () = assert_t_bytes input in
    trace_option (simple_error "untyped UNPACK") @@
    output_opt

  let crypto_hash = typer_1 "HASH" @@ fun t ->
    let%bind () = assert_t_bytes t in
    ok @@ t_bytes ()

  let sender = constant "SENDER" @@ t_address ()

  let source = constant "SOURCE" @@ t_address ()

  let unit = constant "UNIT" @@ t_unit ()

  let amount = constant "AMOUNT" @@ t_tez ()

  let transaction = typer_3 "CALL" @@ fun param amount contract ->
    let%bind () = assert_t_tez amount in
    let%bind contract_param = get_t_contract contract in
    let%bind () = assert_type_value_eq (param , contract_param) in
    ok @@ t_operation ()

  let get_contract = typer_1_opt "CONTRACT" @@ fun _ tv_opt ->
    let%bind tv =
      trace_option (simple_error "get_contract needs a type annotation") tv_opt in
    let%bind tv' =
      trace_strong (simple_error "get_contract has a not-contract annotation") @@
      get_t_contract tv in
    ok @@ t_contract tv' ()

  let abs = typer_1 "ABS" @@ fun t ->
    let%bind () = assert_t_int t in
    ok @@ t_nat ()

  let times = typer_2 "TIMES" @@ fun a b ->
    if eq_2 (a , b) (t_nat ())
    then ok @@ t_nat () else
    if eq_2 (a , b) (t_int ())
    then ok @@ t_int () else
    if (eq_1 a (t_nat ()) && eq_1 b (t_tez ())) || (eq_1 b (t_nat ()) && eq_1 a (t_tez ()))
    then ok @@ t_tez () else
      simple_fail "Multiplying with wrong types"

  let div = typer_2 "DIV" @@ fun a b ->
    if eq_2 (a , b) (t_nat ())
    then ok @@ t_nat () else
    if eq_2 (a , b) (t_int ())
    then ok @@ t_int () else
      simple_fail "Dividing with wrong types"

  let mod_ = typer_2 "MOD" @@ fun a b ->
    if (eq_1 a (t_nat ()) || eq_1 a (t_int ())) && (eq_1 b (t_nat ()) || eq_1 b (t_int ()))
    then ok @@ t_nat () else
      simple_fail "Computing modulo with wrong types"

  let add = typer_2 "ADD" @@ fun a b ->
    if eq_2 (a , b) (t_nat ())
    then ok @@ t_nat () else
    if eq_2 (a , b) (t_int ())
    then ok @@ t_int () else
    if (eq_1 a (t_nat ()) && eq_1 b (t_int ())) || (eq_1 b (t_nat ()) && eq_1 a (t_int ()))
    then ok @@ t_int () else
      simple_fail "Adding with wrong types"

  let constant_typers = Map.String.of_list [
      add ;
      times ;
      div ;
      mod_ ;
      sub ;
      none ;
      some ;
      comparator "EQ" ;
      comparator "NEQ" ;
      comparator "LT" ;
      comparator "GT" ;
      comparator "LE" ;
      comparator "GE" ;
      boolean_operator_2 "OR" ;
      boolean_operator_2 "AND" ;
      map_remove ;
      map_update ;
      int ;
      size ;
      failwith_ ;
      get_force ;
      bytes_pack ;
      bytes_unpack ;
      crypto_hash ;
      sender ;
      source ;
      unit ;
      amount ;
      transaction ;
      get_contract ;
      abs ;
    ]

end

module Compiler = struct
  (*
    Most constants pass through the Transpiler unchanged. So they need to be
    compiled down to Michelson. This is the last step.

    When compiling the constant, we need to provide its arity (through the type
    predicate, defined in `Helpers.Compiler`, and its michelson code.
    In the case of an n-ary constant, we assume that the stack has the form:
    `x1 :: x2 :: x3 ... :: xn :: _`.

    This step requires knowledge of Michelson. Knowledge of
    `Tezos_utils.Michelson` will help too, so that no Michelson has to actually
    be written by hand.
  *)

  include Helpers.Compiler
  open Tezos_utils.Michelson

  let predicates = Map.String.of_list [
    ("ADD" , simple_binary @@ prim I_ADD) ;
    ("SUB" , simple_binary @@ prim I_SUB) ;
    ("TIMES" , simple_binary @@ prim I_MUL) ;
    ("DIV" , simple_binary @@ seq [prim I_EDIV ; i_assert_some_msg (i_push_string "DIV by 0") ; i_car]) ;
    ("MOD" , simple_binary @@ seq [prim I_EDIV ; i_assert_some_msg (i_push_string "MOD by 0") ; i_cdr]) ;
    ("NEG" , simple_unary @@ prim I_NEG) ;
    ("OR" , simple_binary @@ prim I_OR) ;
    ("AND" , simple_binary @@ prim I_AND) ;
    ("PAIR" , simple_binary @@ prim I_PAIR) ;
    ("CAR" , simple_unary @@ prim I_CAR) ;
    ("CDR" , simple_unary @@ prim I_CDR) ;
    ("EQ" , simple_binary @@ seq [prim I_COMPARE ; prim I_EQ]) ;
    ("NEQ" , simple_binary @@ seq [prim I_COMPARE ; prim I_NEQ]) ;
    ("LT" , simple_binary @@ seq [prim I_COMPARE ; prim I_LT]) ;
    ("LE" , simple_binary @@ seq [prim I_COMPARE ; prim I_LE]) ;
    ("GT" , simple_binary @@ seq [prim I_COMPARE ; prim I_GT]) ;
    ("GE" , simple_binary @@ seq [prim I_COMPARE ; prim I_GE]) ;
    ("UPDATE" , simple_ternary @@ prim I_UPDATE) ;
    ("SOME" , simple_unary @@ prim I_SOME) ;
    ("MAP_GET_FORCE" , simple_binary @@ seq [prim I_GET ; i_assert_some_msg (i_push_string "GET_FORCE")]) ;
    ("MAP_GET" , simple_binary @@ prim I_GET) ;
    ("SIZE" , simple_unary @@ prim I_SIZE) ;
    ("FAILWITH" , simple_unary @@ prim I_FAILWITH) ;
    ("ASSERT" , simple_binary @@ i_if (seq [i_failwith]) (seq [i_drop ; i_push_unit])) ;
    ("INT" , simple_unary @@ prim I_INT) ;
    ("ABS" , simple_unary @@ prim I_ABS) ;
    ("CONS" , simple_binary @@ prim I_CONS) ;
    ("UNIT" , simple_constant @@ prim I_UNIT) ;
    ("AMOUNT" , simple_constant @@ prim I_AMOUNT) ;
    ("CALL" , simple_ternary @@ prim I_TRANSFER_TOKENS) ;
    ("SOURCE" , simple_constant @@ prim I_SOURCE) ;
    ("SENDER" , simple_constant @@ prim I_SENDER) ;
    ( "MAP_UPDATE" , simple_ternary @@ seq [dip (i_some) ; prim I_UPDATE ]) ;
  ]

end