first draft for week #2

README.md

@@ -12,9 +12,16 @@
   - Running an example auction contract on a local Playground.
   - Homework.
 
+- [Lecture #2]()
+
+  - Triggering change.
+  - Low-level, untyped on-chain validation scripts.
+  - High-level, typed on-chain validation scripts.
+
 ## Code Examples
 
 - Lecture #1:  [English Auction](code/week01)
+- Lecture #2:  [Simple validation](code/week02)
 
 ## Exercises
 
@@ -32,6 +39,11 @@
   - Compile.
   - Simulate various auction scenarios.
 
+- Week #2
+
+  - Fix and complete the code in the [Homework1](code/week02/src/Week02/Homework1.hs) module.
+  - Fix and complete the code in the [Homework2](code/week02/src/Week02/Homework2.hs) module.
+
 ## Some Plutus Modules
 
 - [`Language.Marlowe.Semantics`](https://github.com/input-output-hk/plutus/blob/master/marlowe/src/Language/Marlowe/Semantics.hs), contains Marlowe types and semantics.

code/week02/src/Week02/Burn.hs

@@ -8,8 +8,6 @@
 {-# LANGUAGE TypeFamilies        #-}
 {-# LANGUAGE TypeOperators       #-}
 
-{-# OPTIONS_GHC -fno-warn-unused-imports #-}
-
 module Week02.Burn where
 
 import           Control.Monad       hiding (fmap)
@@ -27,12 +25,14 @@ import           Ledger.Ada          as Ada
 import           Playground.Contract (printJson, printSchemas, ensureKnownCurrencies, stage)
 import           Playground.TH       (mkKnownCurrencies, mkSchemaDefinitions)
 import           Playground.Types    (KnownCurrency (..))
-import           Prelude             (Semigroup (..), String)
+import           Prelude             (IO, Semigroup (..), String)
 import           Text.Printf         (printf)
 
+{-# OPTIONS_GHC -fno-warn-unused-imports #-}
+
 {-# INLINABLE mkValidator #-}
 mkValidator :: Data -> Data -> Data -> ()
-mkValidator _ _ _ = traceError "NO WAY!"
+mkValidator _ _ _ = traceError "BURNT!"
 
 validator :: Validator
 validator = mkValidatorScript $$(PlutusTx.compile [|| mkValidator ||])

code/week02/src/Week02/FortyTwo.hs

@@ -25,7 +25,7 @@ import           Ledger.Ada          as Ada
 import           Playground.Contract (printJson, printSchemas, ensureKnownCurrencies, stage)
 import           Playground.TH       (mkKnownCurrencies, mkSchemaDefinitions)
 import           Playground.Types    (KnownCurrency (..))
-import           Prelude             (Semigroup (..), String)
+import           Prelude             (IO, Semigroup (..), String)
 import           Text.Printf         (printf)
 
 {-# OPTIONS_GHC -fno-warn-unused-imports #-}
@@ -57,13 +57,13 @@ give amount = do
     logInfo @String $ printf "made a gift of %d lovelace" amount
 
 grab :: forall w s e. AsContractError e => Integer -> Contract w s e ()
-grab r = do
+grab n = 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 $ I r | oref <- orefs]
+        tx      = mconcat [mustSpendScriptOutput oref $ Redeemer $ I n | oref <- orefs]
     ledgerTx <- submitTxConstraintsWith @Void lookups tx
     void $ awaitTxConfirmed $ txId ledgerTx
     logInfo @String $ "collected gifts"

code/week02/src/Week02/Gift.hs

@@ -24,6 +24,8 @@ import           Ledger.Ada          as Ada
 import           Playground.Contract (printJson, printSchemas, ensureKnownCurrencies, stage)
 import           Playground.TH       (mkKnownCurrencies, mkSchemaDefinitions)
 import           Playground.Types    (KnownCurrency (..))
+import           Prelude             (IO, Semigroup (..), String)
+import           Text.Printf         (printf)
 
 {-# OPTIONS_GHC -fno-warn-unused-imports #-}
 
@@ -40,46 +42,6 @@ valHash = Scripts.validatorHash validator
 scrAddress :: Ledger.Address
 scrAddress = scriptAddress validator
 
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-{-
-{-# INLINABLE mkValidator #-}
-mkValidator :: Data -> Data -> Data -> ()
-mkValidator _ _ _ = ()
-
-validator :: Validator
-validator = mkValidatorScript $$(PlutusTx.compile [|| mkValidator ||])
-
 type GiftSchema =
             Endpoint "give" Integer
         .\/ Endpoint "grab" ()
@@ -112,4 +74,3 @@ endpoints = (give' `select` grab') >> endpoints
 mkSchemaDefinitions ''GiftSchema
 
 mkKnownCurrencies []
--}

code/week02/src/Week02/Homework1.hs

@@ -26,7 +26,7 @@ import           Ledger.Ada           as Ada
 import           Playground.Contract  (printJson, printSchemas, ensureKnownCurrencies, stage)
 import           Playground.TH        (mkKnownCurrencies, mkSchemaDefinitions)
 import           Playground.Types     (KnownCurrency (..))
-import           Prelude              (Semigroup (..), String, undefined)
+import           Prelude              (IO, Semigroup (..), String, undefined)
 import           Text.Printf          (printf)
 
 {-# INLINABLE mkValidator #-}

code/week02/src/Week02/Homework2.hs

@@ -30,7 +30,7 @@ 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 (..), String, undefined)
+import           Prelude              (IO, Semigroup (..), String, undefined)
 import           Text.Printf          (printf)
 
 data MyRedeemer = MyRedeemer

code/week02/src/Week02/IsData.hs

@@ -17,6 +17,7 @@ import           Data.Map             as Map
 import           Data.Text            (Text)
 import           Data.Void            (Void)
 import           Plutus.Contract
+import           PlutusTx             (Data (..))
 import qualified PlutusTx
 import           PlutusTx.Prelude     hiding (Semigroup(..), unless)
 import           Ledger               hiding (singleton)
@@ -26,17 +27,16 @@ import           Ledger.Ada           as Ada
 import           Playground.Contract  (printJson, printSchemas, ensureKnownCurrencies, stage)
 import           Playground.TH        (mkKnownCurrencies, mkSchemaDefinitions)
 import           Playground.Types     (KnownCurrency (..))
-import           Prelude              (Semigroup (..), Show, String)
+import           Prelude              (IO, Semigroup (..), String)
 import           Text.Printf          (printf)
 
 newtype MySillyRedeemer = MySillyRedeemer Integer
-    deriving Show
 
 PlutusTx.unstableMakeIsData ''MySillyRedeemer
 
 {-# INLINABLE mkValidator #-}
 mkValidator :: () -> MySillyRedeemer -> ScriptContext -> Bool
-mkValidator () (MySillyRedeemer r) _ = traceIfFalse "wrong redeemer" $ r == 42
+mkValidator _ (MySillyRedeemer r) _ = traceIfFalse "wrong redeemer" $ r == 42
 
 data Typed
 instance Scripts.ValidatorTypes Typed where
@@ -77,7 +77,7 @@ grab r = do
         lookups = Constraints.unspentOutputs utxos      <>
                   Constraints.otherScript validator
         tx :: TxConstraints Void Void
-        tx      = mconcat [mustSpendScriptOutput oref $ Redeemer $ PlutusTx.toData $ MySillyRedeemer r | oref <- orefs]
+        tx      = mconcat [mustSpendScriptOutput oref $ Redeemer $ PlutusTx.toData (MySillyRedeemer r) | oref <- orefs]
     ledgerTx <- submitTxConstraintsWith @Void lookups tx
     void $ awaitTxConfirmed $ txId ledgerTx
     logInfo @String $ "collected gifts"

code/week02/src/Week02/Solution1.hs

@@ -28,7 +28,7 @@ import           Ledger.Ada           as Ada
 import           Playground.Contract  (printJson, printSchemas, ensureKnownCurrencies, stage)
 import           Playground.TH        (mkKnownCurrencies, mkSchemaDefinitions)
 import           Playground.Types     (KnownCurrency (..))
-import           Prelude              (Semigroup (..), String)
+import           Prelude              (IO, Semigroup (..), String)
 import           Text.Printf          (printf)
 
 {-# INLINABLE mkValidator #-}

code/week02/src/Week02/Solution2.hs

@@ -30,7 +30,7 @@ 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 (..), String)
+import           Prelude              (IO, Semigroup (..), String)
 import           Text.Printf          (printf)
 
 data MyRedeemer = MyRedeemer

code/week02/src/Week02/Typed.hs

@@ -27,14 +27,12 @@ import           Ledger.Ada           as Ada
 import           Playground.Contract  (printJson, printSchemas, ensureKnownCurrencies, stage)
 import           Playground.TH        (mkKnownCurrencies, mkSchemaDefinitions)
 import           Playground.Types     (KnownCurrency (..))
-import           Prelude              (Semigroup (..), String)
+import           Prelude              (IO, Semigroup (..), String)
 import           Text.Printf          (printf)
 
 {-# INLINABLE mkValidator #-}
 mkValidator :: () -> Integer -> ScriptContext -> Bool
-mkValidator () r _
+mkValidator _ r _ = traceIfFalse "wrong redeemer" $ r == 42
-    | r == 42   = True
-    | otherwise = False
 
 data Typed
 instance Scripts.ValidatorTypes Typed where