Pathfinder acts as a trusted source of StarkNet data. Each node indepedently verifies the data it receives and ensures that it matches the proofs submitted on Ethereum. In this way, you can trust the data it provides without having to trust the StarkNet gateway or StarkWare at all.

It also provides an RPC API with which you can query StarkNet block, transaction, and event data: https://github.com/eqlabs/pathfinder#json-rpc-api

It can also be a fun first step into some of the more technical aspects underlying StarkNet. Feedback and bug reports are valuable so every node runner implicitly helps grow pathfinder and StarkNet!



Why should I run a Pathfinder node?

Python issues with Pathfinder

StarkNet is in Alpha. Cool.

But what will Beta mean? When should it be beta? Please tell me. Chose all options which are "MVB" or "minimum viable beta". 6 questions.

1. How much **throughput** do you need? ~15TPS like ETH, ~150 TPS, ~1k TPS?
2. On speed of transactions on mainnet: ~10ms, ~1ms, ~10s, ~1s block time what do you think?
3. On pace of releases of Cairo / StarkNet: 1 per month, 1 per 6 month, 1 per 12 month?
4. What do you think about volition and Data availability systems/providers?
- VO & DAL optional, 
- VO mandatory, single DAL
- VO mandatory, various DAL?
5. On cost: ~10% of Ethereum, ~1% of Ethereum, ~0.1% of Ethereum?
6. When do you expect to see beta? ~3, ~6, ~12 months?

**Based on this [Twitter's thread](https://twitter.com/henrlihenrli/status/1599788123092754432)**

What do you think about current StarkNet Alpha and future Beta? What will Beta mean? When should it be beta?

Hello! This is day 3 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 “Conditionals”. Perhaps you can help me?

```python
// The function `abs_eq` should return 1 if its inputs
// are equal or differ only in sign and 0 otherwise.
// Its current implementation is incorrect.
//
// 1. Click on "Run" to see where it fails.
// 2. Fix the body of `abs_eq`, so that the
//    program terminates successfully.

// Returns 1 if |x| = |y| (that is, x = y or x = -y),
// 0 otherwise.
func abs_eq(x: felt, y: felt) -> (bit: felt) {
    if (x == -y) {
        return (bit=1);
    } else {
        return (bit=0);
    }
}

func main() {
    let (bit) = abs_eq(2, -2);
    assert bit = 1;

    let (bit) = abs_eq(2, 3);
    assert bit = 0;

    let (bit) = abs_eq(2, 2);
    assert bit = 1;

    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 make conditional expressions if..then..else in Cairo lang?

I am trying to deploy my contract using this tutorial
[https://medium.com/starknet-edu/deploying-to-starknet-with-the-universal-deployer-contract-c6de07092bfb](https://medium.com/starknet-edu/deploying-to-starknet-with-the-universal-deployer-contract-c6de07092bfb)
But as I follow the steps, I got an error at the contract declaration step: `Unitialized Contract`

Trying to deploy contract with Argent guide but got error Unitialized Contract

Is there any other way to do 2**n without using `pow.cairo`?

Is there any other way to do 2**n without using pow.cairo?

>Hello! This is day 5 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 “Revoked references”. Can you run these 6 steps and write down what you see?

```
// The scope of some types of references in Cairo (e.g., return values of
// functions and temporary variables) is somewhat restricted.
// For example, a call to another function may revoke those references.
//
// 1. Try to run the following code. You should get an error that `x` was revoked
//    (this is because of the second call to `foo`).
// 2. In simple cases, like this one, the compiler can solve this automatically
//    if the "alloc_locals" keyword is used within the function's scope.
//    Add "alloc_locals;" to the beginning of main(), and make sure the code works.
// 3. To understand what happens behind the scenes, replace "alloc_locals;" with
//    "ap += SIZEOF_LOCALS;" - this command allocates memory cells for local variables
//    (you'll need them below) but doesn't enable the mechanism that
//    automatically resolves revoked references.
//    Trying to run the code now should result in the original error.
// 4. Solve the problem manually by copying the value of `x` to a local variable
//    (e.g., "local x2 = x;"). Local variables are not revoked when functions
//    are called.
//    You can read more about local variables [here](https://www.cairo-lang.org/docs/how_cairo_works/consts.html#local-vars).
// 5. You can even use the same name: "local x = x;".
//    This is called "reference rebinding", where the meaning of `x` changes:
//      Before this line, `x` refers to the return value.
//      After that, `x` refers to the local variable.
// 6. A shorter syntax is "let (local x) = foo(10);" which achieves the same goal.
//    Try it!

%builtins output

from starkware.cairo.common.serialize import serialize_word

// Returns a^3 for a != 0 and 1 otherwise.
func foo(a) -> (res: felt) {
    if (a == 0) {
        return (res=1);
    } else {
        return (res=a * a * a);
    }
}

// Outputs the value 10^3 + 5^3.
func main{output_ptr: felt*}() {
    let (x) = foo(10);
    let (y) = foo(5);
    serialize_word(x + y);
    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)*



Cairo Lang / StarkNet: What are Revoked references? What is alloc_locals?

Another question I have is:

**What's easier, adapt the create2 trick in Solidity then transpile or transpile first then adapt in Cairo?**

---

### *From Newton AI:*

*"Create2" is a feature in Solidity, the programming language used to write smart contracts for the Ethereum blockchain. It allows the creation of new contract accounts using a deterministic algorithm, rather than having to send a transaction to create the contract like with the original "create" function. This can be useful in certain situations, such as when creating a contract that is intended to be deployed at a specific address.*

*Transpiling is the process of converting code written in one programming language into another language. This can be useful if a piece of code needs to be run on a platform that only supports a different language, or if it is desired to use a different language's features or syntax.*


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