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I am new to haskell and I am trying to run a few expressions from the English Auction Contract in the repl.

So if I want to run ValidatorHash "f" from the second last line of the Contract in week01, how do I do it in the repl here [nix-shell:~/plutus-pioneer-program/code/week01]$ cabal repl?

What I tried

> import Ledger.ValidatorHash
> Ledger.ValidatorHash "f"
error: Couldn't match expected type ‘PlutusTx.Builtins.Internal.BuiltinByteString’
                  with actual type ‘[Char]’

then

> import PlutusTx.Builtins.Internal
> Ledger.ValidatorHash (BuiltinByteString "f")
error: Couldn't match expected type ‘bytestring-0.10.12.0:Data.ByteString.Internal.ByteString’
                  with actual type ‘[Char]’

then

> import Data.ByString as BS
error: Could not find module ‘Data.ByString’
    Perhaps you meant
      Data.ByteString (needs flag -package-key bytestring-0.10.12.0)
      Data.String (from base-4.14.1.0)

So do I really need to close this repl and figure out the way to open the repl with the flag? Or is there something very obvious that I am missing?


Edit #1: added non-typo error for bytestring

> import Data.ByteString as BS
error: Could not load module ‘Data.ByteString’
    It is a member of the hidden package ‘bytestring-0.10.12.0’.
    Perhaps you need to add ‘bytestring’ to the build-depends in your .cabal file.

Looks like bytestring is hidden. Is it still possible to run ValidatorHash "f" using any other means?


Edit #2

My question was initially specific to find out the origin of 66 when using the token in week01 code as ValidatorHash "f" is taken from this statement in the contract myToken = KnownCurrency (ValidatorHash "f") "Token" (TokenName "T" :| []). But I was unable to evaluate it.

3 Answers 3

1

Somewhere you have a typo. "ByString" should be "ByteString".

1
  • thanks, I changed my final question to address it.
    – Roofi
    Jan 14, 2022 at 9:10
1

It was newbie mistake. There are these lines at the top

{-# LANGUAGE DataKinds                  #-}
{-# LANGUAGE DeriveAnyClass             #-}
{-# LANGUAGE DeriveGeneric              #-}
{-# LANGUAGE DerivingStrategies         #-}
{-# LANGUAGE FlexibleContexts           #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE LambdaCase                 #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE NoImplicitPrelude          #-}
{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE RecordWildCards            #-}
{-# LANGUAGE ScopedTypeVariables        #-}
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE TypeApplications           #-}
{-# LANGUAGE TypeFamilies               #-}
{-# LANGUAGE TypeOperators              #-}

I ran the following in the repl

:set -XDataKinds
:set -XDeriveAnyClass
:set -XDeriveGeneric
:set -XDerivingStrategies
:set -XFlexibleContexts
:set -XGeneralizedNewtypeDeriving
:set -XLambdaCase
:set -XMultiParamTypeClasses
:set -XNoImplicitPrelude
:set -XOverloadedStrings
:set -XRecordWildCards
:set -XScopedTypeVariables
:set -XTemplateHaskell
:set -XTypeApplications
:set -XTypeFamilies
:set -XTypeOperators

and then simply evaluated the expression and it worked!

> Ledger.ValidatorHash "f"
66
0

Perhaps you need to add ‘bytestring’ to the build-depends in your .cabal file.

Do you have a cabal file somewhere? If so, you need to add the bytestring package.

1
  • Instead of making bytestring work, can I just evaluate ValidatorHash "f"? Or do I need to setup some flags (like maybe :set -XTemplateHaskell)? I was successfully able to compile week01 so I was trying to run this expression in the repl.
    – Roofi
    Jan 14, 2022 at 9:48

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