The simplest storage based Solana program thinkable.

lib.rs

use anchor_lang::prelude::*;
use std::mem::size_of;

// This is your program's public key and it will update
// automatically when you build the project.
declare_id!("3Z9mz1eE38sQ5SFMrvnQpxGcrvuTfwy9wu578pto35oV");

#[program]
mod catalyst {
    use super::*;
    pub fn initialize(_ctx: Context<Initialize>) -> Result<()> {
        Ok(())
    }

    pub fn set_x(ctx: Context<Set>, new_x: u64) -> Result<()> {
        msg!("Changed data to: {}!", new_x); // Message will show up in the tx logs
        ctx.accounts.catalyst_storage.x = new_x;
        Ok(())
    }

    //pub fn spawn(ctx: Context<Catalyst>, )
}

#[derive(Accounts)]
pub struct Initialize<'info> {
    #[account(init,
              payer = signer,
              space = size_of::<CatalystStorage>() + 8)]
    pub catalyst_storage: Account<'info, CatalystStorage>,

    #[account(mut)]
    pub signer: Signer<'info>,

    pub system_program: Program<'info, System>,
}

#[derive(Accounts)]
pub struct Set<'info> {
    #[account(mut)]
    pub catalyst_storage: Account<'info, CatalystStorage>,
}

#[account]
pub struct CatalystStorage {
    x: u64,
}

SomeStore.sol

contract SomeStore {
  struct CatalystStorage {
    uint64 x;
  }
  
  CatalystStorage public stg;
  
  constructor() {
    stg = CatalystStorage({x: 0});
  }
  
  function setX(uint64 newX) {
    stg.x = newX; 
  }
}