WASM: Getting Started

# Install Rust
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# Add WASM target
rustup target add wasm32-unknown-unknown

# Install cargo-contract
cargo install cargo-contract --force

cargo contract new my_contract
cd my_contract

#![cfg_attr(not(feature = "std"), no_std, no_main)]

#[ink::contract]
mod my_contract {
    #[ink(storage)]
    pub struct MyContract {
        value: u32,
    }

    impl MyContract {
        #[ink(constructor)]
        pub fn new(init_value: u32) -> Self {
            Self { value: init_value }
        }

        #[ink(message)]
        pub fn get(&self) -> u32 {
            self.value
        }

        #[ink(message)]
        pub fn increment(&mut self) {
            self.value += 1;
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[ink::test]
    fn default_works() {
        let contract = MyContract::new(0);
        assert_eq!(contract.get(), 0);
    }

    #[ink::test]
    fn increment_works() {
        let mut contract = MyContract::new(0);
        contract.increment();
        assert_eq!(contract.get(), 1);
    }
}

#![cfg_attr(not(feature = "std"), no_std, no_main)]

#[ink::contract]
mod counter {
    #[ink(storage)]
    pub struct Counter {
        value: i32,
    }

    impl Counter {
        #[ink(constructor)]
        pub fn new(init_value: i32) -> Self {
            Self { value: init_value }
        }

        #[ink(message)]
        pub fn get(&self) -> i32 {
            self.value
        }

        #[ink(message)]
        pub fn increment(&mut self) {
            self.value += 1;
        }

        #[ink(message)]
        pub fn decrement(&mut self) {
            self.value -= 1;
        }
    }
}