Starknet.id is a third party app that we are familiar with but pls DYOR

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

Newton

Hey team, is the below legit ?https://odyssey.starknet.id/

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

Is starknet.id legit?

Hi, has anyone implemented a minimal proxy (also known as clones), in Cairo? I would like to see an example. I can only find examples for upgraded contracts. 

The idea is to deploy multiple proxy instances pointing to the same implementation contract. 

Something similar to OZ's Clones.sol on Solidity:
https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/proxy/Clones.sol

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

Has anyone implemented a minimal proxy in Cairo lang?

I have a struct with : 

```struct Binary:
felt a:
felt* b:
```

How to return this in a view function?
I see this error:
```
Can't identify return variable
```


how to return struct

Hello! This is day 13 of the 17 days of the Cairo Challenge. And I have no idea how to solve the [playground](https://www.cairo-lang.org/playground/) exercise “Pedersen Hash”.  Perhaps you can help me?

```
// The following code implements a Pedersen hash chain.
// Given the [Pedersen hash](https://docs.starkware.co/starkex-docs/crypto/pedersen-hash-function) function `H`, which
// takes two field elements and returns one representing their hash,
// a hash chain on inputs x_0, x_1, ..., x_n is the result of
// H(H(...H(H(x_0, x_1), x_2), ...,x_{n-1}), x_n)
// For example, the hash chain of (1, 2, 3, 4) is H(H(H(1, 2), 3), 4).
//
// Fix the function `hash_chain` to correctly implement the
// hash chain. Run your code to test it.
//
// Note: Don't use starkware.cairo.common.hash_chain (it computes the chain differently).

// Use the Pedersen builtin.
%builtins pedersen

from starkware.cairo.common.alloc import alloc
from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.cairo.common.hash import hash2

// Computes the Pedersen hash chain on an array of size `length` starting from `data_ptr`.
func hash_chain{hash_ptr: HashBuiltin*}(data_ptr: felt*, length: felt) -> (result: felt) {
    if (length == 2) {
        let (result) = hash2(x=[data_ptr], y=[data_ptr + 1]);
        return (result=result);
    } else {
        // Fix here:
        return (result=123456);
    }
}

func main{pedersen_ptr: HashBuiltin*}() {
    alloc_locals;
    // Allocate a new array.
    let (local data_ptr: felt*) = alloc();
    // Fill the new array with field elements.
    assert [data_ptr] = 314;
    assert [data_ptr + 1] = 159;
    // Run the hash chain.
    let (result) = hash_chain{hash_ptr=pedersen_ptr}(data_ptr=data_ptr, length=2);
    // Check the result.
    assert result = 307958720726328212653290369969069617958360335228383070119367204176047090109;

    // Fill two more cells in the array.
    assert [data_ptr + 2] = 265;
    assert [data_ptr + 3] = 358;
    // Compute the hash chain on all four cells.
    let (result) = hash_chain{hash_ptr=pedersen_ptr}(data_ptr=data_ptr, length=4);
    assert result = 1828757374677754028678056220799392919487521050857166686061558043629802016816;
    return ();
}
```

---

> 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 use Pedersen Hash in StarkNet / Cairo Language?

What is the best way to check if a value is less than another value in a conditional? Say if x > y, then do something


ㅤ
_This question was originally posted on [Triality](https://triality.org/question/491)_

Cairo: Using less than or greater than in conditional

In writing my Cairo program I have the following code:


currNumber is a storage variable:


`@storage_var`


`func currNumber() -> (res : felt):`


`end`


And we have code that calls this value and uses the currNum in a subsequent function:


`...` 


 `let currNum = currNumber.read()`


 `let (res) = findSumDigits(currNum, 0)`


`...`


And I am getting the following error:


Expected expression of type 'felt', got '(res : felt)'.


 let (res) = findSumDigits(currNum, 0)


 ^*****^


﻿  



ㅤ
_This question was originally posted on [Triality](https://triality.org/question/821)_

Cairo Error: Getting Expected expression of type 'felt', got '(res : felt)'

Any nft marketplace has launched on starknet L2?

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

Any NFT marketplace has launched on starknet L2?

does anybody have a working local setup ? I find myself having to run tests on the testnet...

I tried both nile and protostar. the problem is that I can set it up but I don't know how to get access to the accounts that are pre-loaded with ETH. new accounts that I create don't have ETH and I don't have a way to transfer ETH to them..

if anybody has a go-to setup that they can share that'd be much appreciated 🙏

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