Error handling

⚠️ Not implemented ⚠️: This feature is planned for the next update.

Sometimes an operation can fail. For example, if you try to open a file that doesn't exist, or if you try to divide by zero. In Ruda, you can handle these errors using the try keyword.

try {
    let file = io.open("file.txt")
} catch err {
    io.println(err)
}

The try keyword is used to call a function that can fail. If the function fails, the catch block is executed. The catch block is used to handle the error.

The catch block takes a variable that stores the error.

Catch statements

You can have multiple catch statements to handle different errors.

try {
    let file = io.open("file.txt")
} catch err: io.FileNotFound {
    io.println(err.msg())
} catch err {
    io.println(err.msg())
}

Yeet

The yeet keyword is used to throw an error.

fun divide(x: int, y: int)!: int {
    if y == 0 {
        yeet Error("cannot divide by zero")
    }

    return x / y
}

Error

If you dont need to throw an error but you don't care about the error type, you can use the Error type as shown above.

Bang operator

If we don't want to handle the error, we can use the bang operator to ignore the error. It will be forwarded to the caller.

fun divide(x: int, y: int)!: int {
    if y == 0 {
        yeet Error("cannot divide by zero")
    }

    return x / y
}

fun main() {
    let result = divide(10, 0)! // this will crash
}

Error declaration

You can declare an error type using the error keyword.

error DivisionByZeroError(number: int) {
    message: "cannot divide by zero",
    code: 1,
}

This can be used like this:

fun divide(x: int, y: int)!: int {
    if y == 0 {
        yeet DivisionByZeroError(y)
    }

    return x / y
}

The error field code is optional. It can be used to identify the error. Default value is 1.

You can also take message as an argument.

error Error(message: string?) {
    message: {
        if message? {
            return message
        } else {
            return "something went wrong"
        }
    }
    code: 1,
}