Is there any blockchain project contract supporting web2 scripts executable on VIa EVM?

I think it only one Tru (truebit)

Is there any blockchain project contract supporting web2 scripts executable on VIa EVM?

1. Can anyone explain how to get Goerli ETH tokens?

2. Also want to know how to bridge tokens from the Goerli ETH testnet and move them to Goerli2 (StarkNet)?


---

> thank's for your answers, summing up how to transfer funds and how to use Faucet on Ethereum:


1. For receiving ETH on Goerli Test Net, I used [Goerli PoW Faucet](https://goerli-faucet.pk910.de/).
As an alternative, [https://goerlifaucet.com/](https://goerlifaucet.com/) can be used, but it is required to authorize.

2. I installed ArgentX using the links below and transferred funds using the [HashStack service for StarkNet](https://goerli2-bridge.hashstack.finance)

![https://www.bbntimes.com/images/Ethereum_Faucet.jpeg](https://www.bbntimes.com/images/Ethereum_Faucet.jpeg)

StarkNet Faucet: How can I get a Goerli-2 eth faucet tokens (StarkNet)?

Are you able to nest mappings in Cairo like you can in Solidity?

e.g. in Solidity you can do
```solidity
mapping(address => mapping(uint256 => bool));
```
is this doable in Cairo? I want to do something similar to

```cairo

func mappingA(value: felt) -> func mappingB(value: felt)  -> (value: felt){
}
```

mapping(x, y) -> (z) is not gonna work, here is some context:

I'm working through the sample ERC721_Metadata.cairo and ERC721_Metadata_Base contract shown here https://github.com/starknet-edu/starknet-erc721/tree/main/contracts/token/ERC721

It looks like from what I can tell the tokenUri is set for each domain, and even though calling the @view function does take in a tokenId, calling to set the tokenUri does not and it's not clear to me how that mapping could exist otherwise. So I wanted to modify the contract to have a token_id -> token_uri mapping. Because of the way those mappings exist though, you need to provide both the token_uri_len: felt and token_uri: felt*  when writing them. This means it can only be done once, otherwise you'd need a specific @storage_var for every token that's minted, just to hold it's tokenuri. I was hoping to do something like 

```cairo
// Represents a tokenUri
struct TokenUri {
    // The length of the token bytes
    token_uri_len: felt,
    // The pointer to the beginning of the token uri bytes
    token_uri: felt*,
}

@storage_var
func token_uris(token_id: felt) -> (token_uri: TokenUri) {
}
```


But because of the token_url: felt*  pointer in that struct, it can't be used as a storage variable return type. It gives an error when I try to compile showing
```cairo
starknet_contracts/ERC721_Metadata.cairo:29:36: The return type of storage variables must be a felts-only type (cannot contain pointers).
func token_uris(token_id: felt) -> (token_uri: TokenUri) {
```

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

Are you able to nest mappings in Cairo like you can in Solidity?

Hey everyone!

I am trying to unpack nested tuples into felts t pass as calldata to a contract via a proxy call.

await signer.send_transaction(admin, proxy_contract.contract_address, 'createSyntheticAsset', [
       *test_synthetic_asset.to_tuple() 
    ])

But this fails with this error: TypeError: '<' not supported between instances of 'tuple' and 'int' 

does anyone have an Idea about this?

_This question was originally posted on [StarkNet Discord](https://www.newton.so/view?tags=discord)_

A TypeError while unpacking nested tuples into felts

Hello! This is day 17 of the 17 days of the Cairo Challenge. In this challenge I want to ask you [install](https://www.cairo-lang.org/docs/quickstart.html) Cairo and try to launch your first program. What have you implemented as your first Cairo language program?

**Step 1**
```solidity
// 1. Make sure that you installed dev packages on your device
sudo apt install -y libgmp3-dev // Linux
brew install gmp // Mac OS
```
**Step 2**
```solidity
// 2. Install Cairo using Python virtual environment
python3.9 -m venv ~/cairo_venv
source ~/cairo_venv/bin/activate
pip3 install ecdsa fastecdsa sympy;
pip3 install cairo-lang;
```
**Step 3**
```bash
// 3. Make sure you have python 3.9. Because Cairo was tested with python3.9. To make it work with python3.6, you will have to install contextvars:
pip3 install contextvars
```
**Step 4**
```python
// 4. Write your program
// Create a file, named hello.cairo, with the following lines:
 
func main() {
		// edit me: you can add here any output, best program wins the challenge
    ret;
}

```solidity
//5. Compile your program
cairo-compile hello.cairo --output hello_compiled.json
```
**Last step**
```solidity

//6. Run:
cairo-run \
  --program=hello_compiled.json --print_output \
  --print_info --relocate_prints

//7. Debug:
//You can open the Cairo tracer by providing the --tracer flag to cairo-run. Then open it at http://localhost:8100/.
```
If you have questions, create them on Newton and we will help!

---
> Answers to this question are a part of the ✨ 17 days of Cairo Lang with Playground & Newton. ✨
> 

*Vote for your favorite answer - the best answer will win a $10 award. A new day – a new reward! During the next 17 days, our goal is to attract more developers to the Cairo language and to systematize the knowledge of Cairo lang. [Read rules](https://www.notion.so/17-days-of-Cairo-Lang-with-Newton-550dfcda6a2d449ca468be293c776578)*

How to install Cairo v0.10.0 on my device?

Hey guys,

I am having issue with generating _abi.json file when I use namespace,
Please see example below.

Does someone know solution of how to generate _abi.json file when namespace is used? I really need help 🙏 

This code generates starknet_abi.json

%lang starknet
from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.starknet.common.syscalls import get_caller_address

@External
   func store_name{syscall_ptr: felt, pedersen_ptr: HashBuiltin, range_check_ptr}(_count: felt) -> (even : felt) {
      alloc_locals;
      local even;

      let (caller) = get_caller_address();
      if (_count == 2) {
         even = 1;
      }
      return (even=even);
   }
=============================================================
This code does not generates starknet_abi.json (please see use of  namespace)

%lang starknet
from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.starknet.common.syscalls import get_caller_address

namespace ToMoon {
@External
   func store_name{syscall_ptr: felt, pedersen_ptr: HashBuiltin, range_check_ptr}(_count: felt) -> (even : felt) {
      alloc_locals;
      local even;

      let (caller) = get_caller_address();
      if (_count == 2) {
         even = 1;
      }
      return (even=even);
   }
}



Issue with generating _abi.json file 

Is memory immutable in Cairo? In what situations is it and in what situations is it not?


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/381)_

Immutable Memory in Cairo

How does Account Abstraction improve the UX compared to other methods?

---

This question is participating in [Newton Bounties | Incentivized Test Program](https://www.notion.so/Newton-Bounties-Incentivized-Test-Program-94322ad48e7d40a3adcf36f6b26174cd) Every verified valid question gets $10 USDC (mainnet)

Popular tags

Is there any blockchain project contract supporting web2 scripts executable on VIa EVM?

0 answers

Your answer

Related

You may find useful