Lars Brünjes
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Randomness in a smart contract
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Validation is deterministic, so decidedly non-random. And this is a desirable feature, because it means you can validate a transaction off-chain before ever submitting it, thus being sure you'll never ...

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How can smart contracts interact each other?
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It can't. But that doesn't mean different smart contracts can't interact. The interaction must simply happen in the same transaction. As an example, imagine you have some Uniswap-like liquidity pool ...

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What has happened to the KEVM?
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Development is alive and kicking. Alongside our native smart contract language Plutus, we are still on track with the KEVM and its support for languages like Solidity and Glow.

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14 votes
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Do old UTXO's ever get pruned from the blockchain?
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15 votes

No, it never gets pruned. One of the appealing features of blockchain is that the history stays there forever. The size of the blockchain grows roughly linearly (ignoring the effect of adoption), ...

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Plutus Pioneer Program - Lecture #1 Problem with cabal build
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It looks like your cabal version is too old. You can make sure you have the right one if you first start a nix-shell at the top-level directory of the plutus-repository, then cd to the code folder of ...

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9 votes
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Hardcoding currency symbol and token name in validator script
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7 votes

The problem is in your sealsToken function, where you use a ByteString-literal. This is not possible if you want to compile to Plutus Script. A trick to work around this issue is to add an additional ...

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11 votes
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How does the hardfork combinator work?
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You can get the inside view by Edsko de Vries, creator of the hardfork combinator, here: https://youtu.be/D8OTZULEsaI

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9 votes
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Blockchain Simulator Chokes on Validation Error
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The problem is that in the off-chain wallet code, after submitting the transaction, there is a line of code that waits for the transaction to be confirmed. Seeing as the transaction is invalid, it ...

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12 votes
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What decisions are left to the slot leader?
5 votes

The Haskell reference implementation of the Cardano node, leaves no such decisions to the slot leader, and most (if not all) are using that node implementation. As far as the Cardano protocol is ...

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Validators for Asset Type
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No validation happens for outputs: Anybody can send anything with arbitrary datum to any address. So in your example, those 100 USDT would indeed be locked forever.

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7 votes
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Confused by compilation message in plutus playground (week 5 pioneer program)
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4 votes

The Playground needs some boilerplate added to a module: mkSchemaDefinitions ''NAMEOFYOURSCHEMA mkKnownCurrencies []

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4 votes
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Why does my test of Plutus contract crash?
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3 votes

Currency symbols can't be arbitrary byte strings, they must consist of hexadecimal digits. So you can't use Token, and the error message is complaining about the T. Use something like ff instead.

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10 votes
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How can I write unit tests for Plutus contracts?
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You can use the EmulatorTrace monad introduced in Lecture #4 for unit testing. You find examples of such tests in https://github.com/input-output-hk/plutus/tree/master/plutus-use-cases/test/Spec .

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Logistics of Developing Contracts
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All the techniques you have learned for development on the Playground (or using the EmulatorTrace-monad) will still be valuable and relevant for Goguen. The only difference is that with Goguen, you ...

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5 votes
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How is a transaction output's address generated?
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I am not sure I understand the question... First of all, scripts do not "generate transactions", but validate transactions. Transactions are generated by wallets (and off-chain wallet code). ...

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Are there guides for Router Contracts available (now or in the near future)?
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Seeing as Plutus is brand new and that our Pioneers are the very first people who every write Plutus contracts, there are no best practices yet - and we hope our pioneers will help us discover and ...

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Is there any eth_sign equivalent signing method in plutus?
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You can find functions for message signing and signature checking in packacke plutus-ledger, module Ledger.Oracle. Also, why whould you need a smart contract for this?

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