New to (Secure) Ruby? See the Red Paper!

(Secure) Ruby to Liquidity w/ ReasonML Syntax / Michelson (Source-to-Source) Cross-Compiler Cheat Sheet / White Paper

What's Michelson? What's Liquidity?

The Liquidity language lets you programm (crypto) contracts with (higher-level type-safe functional) OCaml or ReasonML syntax compiling to (lower-level) Michelson stack machine bytecode.

By Example

Let's Count - 0, 1, 2, 3

Ruby • Liquidity (w/ ReasonML)

Ruby

"Classic" Style

type :Storage, Integer

init [],
def storage()
  0
end

entry [Integer],
def inc( by, storage )
  [[], storage + by]
end

"Modern" Style with Language Syntax Pragmas

type Storage = Integer

init [],
def storage()
  0
end

entry [Integer],
def inc( by, storage )
  [[], storage + by]
end

(Source: contracts/counter.rb)

Liquidity (w/ ReasonML)

gets cross-compiled to:

type storage = int;

let%init storage = () => {
  0;
};

let%entry inc = (by: int, storage) => {
  ([], storage + by);
};

(Source: contracts/counter.reliq)

Test, Test, Test

Note: For (local) testing you can run the "Yes, It's Just Ruby" version with the michelson testnet "simulator" library. See /michelson » . Example:

storage  = storage()
# => calling storage()...
# => returning:
# => 0
_, storage = inc( 2, storage )
# => calling inc( 2, 0 )...
# => returning:
# => [[], 2]
_, storage = inc( 1, storage )
# => calling inc( 1, 2 )...
# => returning:
# => [[], 3]

Let's Vote

Ruby • Liquidity (w/ ReasonML)

Ruby

"Classic" Style

type :Storage, Map‹String→Integer›

init [],
def storage()
  {"ocaml" => 0, "reason" => 0, "ruby" => 0}
end

entry [String],
def vote( choice, votes )
  amount = Current.amount
  if amount < 5.tz
    failwith( "Not enough money, at least 5tz to vote" )
  else
    match Map.find(choice, votes), {
      None: ->()  { failwith( "Bad vote" ) },
      Some: ->(x) { votes = Map.add(choice, x + 1, votes); [[], votes] }}
  end
end

"Modern" Style with Language Syntax Pragmas

type Storage = Map‹String→Integer›

init [],
def storage()
  {"ocaml" => 0, "reason" => 0, "ruby" => 0}
end

entry [String],
def vote( choice, votes )
  amount = Current.amount
  if amount < 5.tz
    failwith( "Not enough money, at least 5tz to vote" )
  else
    match Map.find(choice, votes), {
      | None    => { failwith( "Bad vote" ) },
      | Some(x) => { votes = Map.add(choice, x + 1, votes); [[], votes] }}
  end
end

(Source: contracts/vote.rb)

Aside - Type-Safe Function Signature Shortcuts ("Auto-Completion")

Short Version	Long Version
`init []`	`sig :init, [] => [Storage]`
`entry [String]`	`sig :entry, [String, Storage] => [Array‹Operation›, Storage]`
`sig [Address, Address, Nat]`¹	`sig [Address, Address, Nat, Storage] => [Array‹Operation›, Storage]`
`sig [Address, BigMap‹Address→Account›] => [Account]`²	`sig [Address, BigMap‹Address→Account›] => [Account]`

¹: The signature is missing the return type - "auto-completes" Storage parameter and return type; for no return type use [].

²: No magic "auto-completion". Short version is the same as the long version.

Liquidity (w/ ReasonML)

gets cross-compiled to:

type storage = map(string, int);

let%init storage = () => {
  Map([("ocaml", 0), ("reason", 0), ("ruby", 0)]);
};

let%entry vote = (choice: string, votes) => {
  let amount = Current.amount();
  if (amount < 5.00tz) {
    failwith("Not enough money, at least 5tz to vote");
  } else {
    switch (Map.find(choice, votes)) {
    | None    => failwith("Bad vote")
    | Some(x) =>
        let votes = Map.add(choice, x + 1, votes);
        ([], votes);
    };
  };
};

(Source: contracts/vote.reliq)

Test, Test, Test

Note: For (local) testing you can run the "Yes, It's Just Ruby" version with the michelson testnet "simulator" library. See /michelson » . Example:

storage  = storage()
#=> calling storage()...
#=> returning:
#=> {"ocaml"=>0, "reason"=>0, "ruby"=>0}
_, storage = vote( "ruby", storage )
#=> calling vote( "ruby", {"ocaml"=>0, "reason"=>0, "ruby"=>0} )...
#=> !! RuntimeError: failwith - Not enough money, at least 5tz to vote

Current.amount = 10.tz

_, storage = vote( "ruby", storage )
#=> calling vote( "ruby", {"ocaml"=>0, "reason"=>0, "ruby"=>0} )...
#=> returning:
#=> [[], {"ocaml"=>0, "reason"=>0, "ruby"=>1}]
_, storage = vote( "reason", storage )
#=> calling vote( "reason", {"ocaml"=>0, "reason"=>0, "ruby"=>1} )...
#=> returning:
#=> [[], {"ocaml"=>0, "reason"=>1, "ruby"=>1}]
_, storage = vote( "python", storage )
#=> calling vote( "python", {"ocaml"=>0, "reason"=>1, "ruby"=>1} )...
#=> !! RuntimeError: failwith - Bad vote

Minimum Viable Token

Ruby • Liquidity (w/ ReasonML)

Ruby

"Classic" Style

type :Account, {
  balance:    Nat,
  allowances: Map‹Address→Nat› }


type :Storage, {
  accounts:     BigMap‹Address→Account›,
  version:      Nat,
  total_supply: Nat,
  decimals:     Nat,
  name:         String,
  symbol:       String,
  owner:        Address }


init [Address, Nat, Nat, String, String],
def storage( owner, total_supply, decimals, name, symbol )
  owner_account = Account.new( total_supply, {} )
  accounts      = Map.add( owner, owner_account, {} )
  Storage.new( accounts, 1.p, total_supply, decimals, name, symbol, owner )
end


sig [Address, BigMap‹Address→Account›] => [Account],
def get_account(a, accounts)
  match Map.find(a, accounts), {
    None: ->()        { Account.new( 0.p, {} ) },  ## fix: allow (struct) init with keys too
    Some: ->(account) { account }}
end


sig [Address, Address, Nat],
def perform_transfer(from, dest, tokens, storage)
  accounts = storage.accounts
  account_sender = get_account( from, accounts )
  new_account_sender =
    match is_nat(account_sender.balance - tokens), {
     None: ->()  { failwith( "Not enough tokens for transfer", account_sender.balance ) },
     Some: ->(b) { account_sender.update( balance: b )}
    }

  accounts = Map.add(from, new_account_sender, accounts)
  account_dest = get_account( dest, accounts )
  new_account_dest = account_dest.update( balance: account_dest.balance + tokens )
  accounts = Map.add(dest, new_account_dest, accounts)

  [[], storage.update( accounts: accounts )]
end


entry [Address, Nat],
def transfer( dest, tokens, storage )
  perform_transfer( Current.sender, dest, tokens, storage )
end


entry [Address, Nat],
def approve( spender, tokens, storage )
  account_sender = get_account( Current.sender, storage.accounts)

  account_sender = account_sender.update( allowances:
      if tokens == 0.p
        Map.remove( spender, account_sender.allowances )
      else
        Map.add( spender, tokens, account_sender.allowances )
      end )

  storage = storage.update( accounts: Map.add( Current.sender, account_sender, storage.accounts))
  [[], storage]
end


entry [Address, Address, Nat],
def transfer_from( from, dest, tokens, storage)
  account_from = get_account( from, storage.accounts )
  new_allowances_from =
    match Map.find( Current.sender, account_from.allowances ), {
      None: ->()        { failwith( "Not allowed to spend from", from ) },
      Some: ->(allowed) {
        match is_nat(allowed - tokens), {
          None: ->() { failwith( "Not enough allowance for transfer", allowed ) },
          Some: ->(allowed) {
            if allowed == 0.p
              Map.remove( Current.sender, account_from.allowances )
            else
              Map.add( Current.sender, allowed, account_from.allowances )
            end
          }
        }
      }
    }
  account_from = account_from.update( allowances: new_allowances_from )
  storage = storage.update( accounts: Map.add( from, account_from, storage.accounts )
  perform_transfer( from, dest, tokens, storage )
end


entry [Address, Nat],
def create_account( dest, tokens, storage )
  if Current.sender != storage.owner
    failwith( "Only owner can create accounts" )
  end
  perform_transfer( storage.owner, dest, tokens, storage )
end

"Modern" Style with Language Syntax Pragmas

type Account   = {
  balance      : Nat,
  allowances   : Map‹Address→Nat› }


type Storage   = {
  accounts     : BigMap‹Address→Account›,
  version      : Nat,
  total_supply : Nat,
  decimals     : Nat,
  name         : String,
  symbol       : String,
  owner        : Address }


init [Address, Nat, Nat, String, String],
def storage( owner, total_supply, decimals, name, symbol )
  owner_account = Account.new( total_supply, {} )
  accounts      = Map.add( owner, owner_account, {} )
  Storage.new( accounts, 1p, total_supply, decimals, name, symbol, owner )
end


sig [Address, BigMap‹Address→Account›] => [Account],
def get_account(a, accounts)
  match Map.find(a, accounts), {
    | None          => { Account.new( 0p, {} ) },  ## fix: allow (struct) init with keys too
    | Some(account) => { account }}
end


sig [Address, Address, Nat],
def perform_transfer(from, dest, tokens, storage)
  accounts = storage.accounts
  account_sender = get_account( from, accounts )
  new_account_sender =
    match is_nat(account_sender.balance - tokens), {
     | None     => { failwith( "Not enough tokens for transfer", account_sender.balance ) },
     | Some(b)  => { account_sender {...balance: b } }
    }

  accounts = Map.add(from, new_account_sender, accounts)
  account_dest = get_account( dest, accounts )
  new_account_dest = account_dest {...balance: account_dest.balance + tokens }
  accounts = Map.add(dest, new_account_dest, accounts)

  [[], storage {...accounts: accounts }]   
end


entry [Address, Nat],
def transfer( dest, tokens, storage )
  perform_transfer( Current.sender, dest, tokens, storage )
end


entry [Address, Nat],
def approve( spender, tokens, storage )
  account_sender = get_account( Current.sender, storage.accounts)

  account_sender = {...allowances: 
      if tokens == 0p
        Map.remove( spender, account_sender.allowances )
      else
        Map.add( spender, tokens, account_sender.allowances )
      end }

  storage = {...accounts: Map.add( Current.sender, account_sender, storage.accounts) }
  [[], storage]
end


entry [Address, Address, Nat],
def transfer_from( from, dest, tokens, storage)
  account_from = get_account( from, storage.accounts )
  new_allowances_from =
    match Map.find( Current.sender, account_from.allowances ), {
      | None          => { failwith( "Not allowed to spend from", from ) },
      | Some(allowed) => {
        match is_nat(allowed - tokens), {
          | None          => { failwith( "Not enough allowance for transfer", allowed ) },
          | Some(allowed) => {
            if allowed == 0p
              Map.remove( Current.sender, account_from.allowances )
            else
              Map.add( Current.sender, allowed, account_from.allowances )
            end
          }
        }
      }
    }
  account_from = {... allowances: new_allowances_from }
  storage = {... accounts: Map.add( from, account_from, storage.accounts ) }
  perform_transfer( from, dest, tokens, storage )
end


entry [Address, Nat],
def create_account( dest, tokens, storage )
  if Current.sender != storage.owner
    failwith( "Only owner can create accounts" )
  end
  perform_transfer( storage.owner, dest, tokens, storage )
end

(Source: contracts/token.rb)

Liquidity (w/ ReasonML)

gets cross-compiled to:

type account = {
  balance: nat,
  allowances: map(address, nat),
};

type storage = {
  accounts: big_map(address, account),
  version: nat /* version of token standard */,
  totalSupply: nat,
  decimals: nat,
  name: string,
  symbol: string,
  owner: address,
};

let%init storage = (owner, totalSupply, decimals, name, symbol) => {
  let owner_account = {balance: totalSupply, allowances: Map};
  let accounts = Map.add(owner, owner_account, BigMap);
  {accounts, version: 1p, totalSupply, decimals, name, symbol, owner};
};

let get_account = ((a, accounts: big_map(address, account))) =>
  switch (Map.find(a, accounts)) {
  | None => {balance: 0p, allowances: Map}
  | Some(account) => account
  };

let perform_transfer = ((from, dest, tokens, storage)) => {
  let accounts = storage.accounts;
  let account_sender = get_account((from, accounts));
  let new_account_sender =
    switch (is_nat(account_sender.balance - tokens)) {
    | None =>
      failwith(("Not enough tokens for transfer", account_sender.balance))
    | Some(b) => account_sender.balance = b
    };
  let accounts = Map.add(from, new_account_sender, accounts);
  let account_dest = get_account((dest, accounts));
  let new_account_dest = account_dest.balance = account_dest.balance + tokens;
  let accounts = Map.add(dest, new_account_dest, accounts);
  ([], storage.accounts = accounts);
};

let%entry transfer = ((dest, tokens), storage) =>
  perform_transfer((Current.sender(), dest, tokens, storage));

let%entry approve = ((spender, tokens), storage) => {
  let account_sender = get_account((Current.sender(), storage.accounts));
  let account_sender =
    account_sender.allowances = (
      if (tokens == 0p) {
        Map.remove(spender, account_sender.allowances);
      } else {
        Map.add(spender, tokens, account_sender.allowances);
      }
    );
  let storage =
    storage.accounts =
      Map.add(Current.sender(), account_sender, storage.accounts);
  ([], storage);
};

let%entry transferFrom = ((from, dest, tokens), storage) => {
  let account_from = get_account((from, storage.accounts));
  let new_allowances_from =
    switch (Map.find(Current.sender(), account_from.allowances)) {
    | None => failwith(("Not allowed to spend from", from))
    | Some(allowed) =>
      switch (is_nat(allowed - tokens)) {
      | None => failwith(("Not enough allowance for transfer", allowed))
      | Some(allowed) =>
        if (allowed == 0p) {
          Map.remove(Current.sender(), account_from.allowances);
        } else {
          Map.add(Current.sender(), allowed, account_from.allowances);
        }
      }
    };
  let account_from = account_from.allowances = new_allowances_from;
  let storage =
    storage.accounts = Map.add(from, account_from, storage.accounts);
  perform_transfer((from, dest, tokens, storage));
}

let%entry createAccount = ((dest, tokens), storage) => {
  if (Current.sender() != storage.owner) {
    failwith("Only owner can create accounts");
  };
  perform_transfer((storage.owner, dest, tokens, storage));
};

(Source: contracts/token.reliq)

Bonus: (Secure) Ruby to SmartPy to SmartML / Michelson (Source-to-Source) Cross-Compiler Cheat Sheet

The SmartPy¹ library lets you program contracts in Python (see Introducing SmartPy) compiling to SmartML and onto Michelson bytecode.

¹: Upcoming / Planned for Summer 2019

Let's Play Nim - The Ancient Math Subtraction Game

Ruby • Python (w/ SmartPy)

Ruby

Nim is a mathematical game of strategy in which two players take turns removing objects from distinct heaps. On each turn, a player must remove at least one object, and may remove any number of objects provided they all come from the same heap. The goal of the game is to avoid taking the last object.

(Source: Nim @ Wikipedia)

####################################
# Nim Game Contract

sig [Integer, Option(Integer), Bool],
def setup( size, bound=nil, winner_is_last=false)
  @bound          = bound
  @winner_is_last = winner_is_last

  @deck           = Array( 1...size+1 )  ## e.g. [1,2,3,4,...]
  @size           = size
  @next_player    = 1
  @claimed        = false
  @winner         = 0
end

# cell - representing a cell from an array
# k    - a quantity to remove from this cell
sig [Integer, Integer],  
def remove( cell, k )
  assert 0 <= cell
  assert cell < @size
  assert 1 <= k
  assert k <= @bound   if @bound
  assert k <= @deck[cell]

  @deck[cell] -=  k
  @nextPlayer = 3 - @nextPlayer   ## toggles between 1|2
end

def claim
  assert @deck.sum == 0

  @claimed = true
  if @winner_is_last
    @winner = 3 - @nextPlayer
  else
    @winner = @nextPlayer
end

Or using an alternative "meta" parameterized contract template / factory:

####################################
# Nim Game Contract Template
#
# Parameter Options:
# - bound          (default: nil)
# - winner_is_last (default: false)

sig [Integer],
def setup( size )
  @deck           = Array( 1...size+1 )  ## e.g. [1,2,3,4,...]
  @size           = size
  @next_player    = 1
  @claimed        = false
  @winner         = 0
end

# cell - representing a cell from an array
# k    - a quantity to remove from this cell
sig [Integer, Integer],  
def remove( cell, k )
  assert 0 <= cell
  assert cell < @size
  assert 1 <= k
  if $DEFINED[:bound]
    assert k <= $PARA[:bound]
  end
  assert k <= @deck[cell]

  @deck[cell] -=  k
  @nextPlayer = 3 - @nextPlayer   ## toggles between 1|2
end

def claim
  assert @deck.sum == 0

  @claimed = true
  if $TRUE[:winner_is_last]
    @winner = 3 - @nextPlayer
  else
    @winner = @nextPlayer
  end
end

Python (w/ SmartPy)

gets cross-compiled to:

import smartpy as sp

class NimGame(sp.Contract):
    def __init__(self, size, bound = None, winnerIsLast = False):
        self.bound        = bound
        self.winnerIsLast = winnerIsLast
        self.init(deck       = sp.range(1, size + 1),
                  size       = size,
                  nextPlayer = 1,
                  claimed    = False,
                  winner     = 0)

    @sp.message
    def remove(self, data, params):
        cell = params.cell
        k = params.k
        sp.check(0 <= cell)
        sp.check(cell < data.size)
        sp.check(1 <= k)
        if self.bound is not None:
            sp.check(k <= self.bound)
        sp.check(k <= data.deck[cell])
        sp.set(data.deck[cell], data.deck[cell] - k)
        sp.set(data.nextPlayer, 3 - data.nextPlayer)

    @sp.message
    def claim(self, data, params):
        sp.check(sp.sum(data.deck) == 0)
        sp.set(data.claimed, True)
        if self.winnerIsLast:
            sp.set(data.winner, 3 - data.nextPlayer)
        else:
            sp.set(data.winner, data.nextPlayer)

License

The (secure) ruby cross-compiler scripts are dedicated to the public domain. Use it as you please with no restrictions whatsoever.

Request for Comments (RFC)

Send your questions and comments to the ruby-talk mailing list. Thanks!

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(Secure) Ruby to Liquidity w/ ReasonML Syntax / Michelson (Source-to-Source) Cross-Compiler Cheat Sheet / White Paper

By Example

Let's Count - 0, 1, 2, 3

Ruby

Liquidity (w/ ReasonML)

Test, Test, Test

Let's Vote

Ruby

Liquidity (w/ ReasonML)

Test, Test, Test

Minimum Viable Token

Ruby

Liquidity (w/ ReasonML)

Bonus: (Secure) Ruby to SmartPy to SmartML / Michelson (Source-to-Source) Cross-Compiler Cheat Sheet

Let's Play Nim - The Ancient Math Subtraction Game

Ruby

Python (w/ SmartPy)

License

Request for Comments (RFC)