Typed version of Plutus Pionneers homework01 (week02)

Question

I've tried to code a typed version of the first homework exercise. It compiles but fails to render in the playground...

{-# LANGUAGE DataKinds           #-}
{-# LANGUAGE FlexibleContexts    #-}
{-# LANGUAGE NoImplicitPrelude   #-}
{-# LANGUAGE OverloadedStrings   #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TemplateHaskell     #-}
{-# LANGUAGE TypeApplications    #-}
{-# LANGUAGE TypeFamilies        #-}
{-# LANGUAGE TypeOperators       #-}

import           Control.Monad        hiding (fmap)
import           GHC.Generics         (Generic)
import           Data.Aeson           (FromJSON, ToJSON)
import           Data.Map             as Map
import           Data.Text            (Text)
import           Data.Void            (Void)
import           Plutus.Contract      hiding (when)
import           PlutusTx             (Data (..))
import qualified PlutusTx
import           PlutusTx.Prelude     hiding (Semigroup(..), unless)
import           Ledger               hiding (singleton)
import           Ledger.Constraints   as Constraints
import qualified Ledger.Scripts       as Scripts
import qualified Ledger.Typed.Scripts as Scripts
import           Ledger.Ada           as Ada
import           Playground.Contract  (printJson, printSchemas, ensureKnownCurrencies, stage, ToSchema)
import           Playground.TH        (mkKnownCurrencies, mkSchemaDefinitions)
import           Playground.Types     (KnownCurrency (..))
import           Prelude              (Semigroup (..))
import           Text.Printf          (printf)

newtype DuoBoolRedeemer = DuoBoolRedeemer (Bool, Bool)
    deriving (Generic, ToSchema)

PlutusTx.unstableMakeIsData ''DuoBoolRedeemer

{-# INLINABLE mkValidator #-}
-- This should validate if and only if the two Booleans in the redeemer are equal!
mkValidator :: () -> DuoBoolRedeemer -> ValidatorCtx -> Bool
mkValidator _ (DuoBoolRedeemer (b1,b2)) _ = traceIfFalse "wrong redeemer" $ b1 == b2

data Typed
instance Scripts.ScriptType Typed where
    type instance DatumType Typed = ()
    type instance RedeemerType Typed = DuoBoolRedeemer

inst :: Scripts.ScriptInstance Typed
inst = Scripts.validator @Typed
    $$(PlutusTx.compile [|| mkValidator ||])
    $$(PlutusTx.compile [|| wrap ||])
  where
    wrap = Scripts.wrapValidator @() @DuoBoolRedeemer

validator :: Validator
validator = Scripts.validatorScript inst

valHash :: Ledger.ValidatorHash
valHash = Scripts.validatorHash validator

scrAddress :: Ledger.Address
scrAddress = ScriptAddress valHash

type GiftSchema =
    BlockchainActions
        .\/ Endpoint "give" Integer
        .\/ Endpoint "grab" DuoBoolRedeemer

give :: (HasBlockchainActions s, AsContractError e) => Integer -> Contract w s e ()
give amount = do
    let tx = mustPayToTheScript () $ Ada.lovelaceValueOf amount
    ledgerTx <- submitTxConstraints inst tx
    void $ awaitTxConfirmed $ txId ledgerTx
    logInfo @String $ printf "made a gift of %d lovelace" amount

grab :: forall w s e. (HasBlockchainActions s, AsContractError e) => DuoBoolRedeemer -> Contract w s e ()
grab bs = do
    utxos <- utxoAt scrAddress
    let orefs   = fst <$> Map.toList utxos
        lookups = Constraints.unspentOutputs utxos      <>
                  Constraints.otherScript validator
        tx :: TxConstraints Void Void
        tx      = mconcat [mustSpendScriptOutput oref $ Redeemer $ PlutusTx.toData bs | oref <- orefs]
    ledgerTx <- submitTxConstraintsWith @Void lookups tx
    void $ awaitTxConfirmed $ txId ledgerTx
    logInfo @String $ "collected gifts"

endpoints :: Contract () GiftSchema Text ()
endpoints = (give' `select` grab') >> endpoints
  where
    give' = endpoint @"give" >>= give
    grab' = endpoint @"grab" >>= grab

mkSchemaDefinitions ''GiftSchema

mkKnownCurrencies []

I don't understand why it fails. In the playground, for the "grab" action I have the message "Unsuported non record constructor". I think the problem is with ToSchema which may only accept reccords, but if I don't use it, I have an error message requiring it... I don't understand.

Answer 1

I'm no expert, but can you try a: .\/ Endpoint "grab" (Bool, Bool)

Given that the simulator, imho, only expects simpler things