Values, functions, and control flow

Raven code usually begins with values and plain functions. A function does not need a class wrapper when it represents a standalone operation.

Choose immutable or mutable bindings

Use let when a name will continue to refer to the same value. Use var when reassignment is part of the algorithm:

let greeting = "Hello"
var attempts = 0

attempts = attempts + 1

let does not make an object deeply immutable. It means the local name itself will not be reassigned.

Declare a function with func. Parameter and return types make its boundary visible, while local types can often be inferred:

func ShippingCost(weightKg: decimal) -> decimal {
    let basePrice = 12.50m
    return basePrice + weightKg * 1.75m
}

Use a top-level function for parsing, validation, formatting, lookup, or a workflow step that has no natural owning object.

An if can produce a value:

let label = if attempts == 0 {
    "Ready"
} else {
    "Retrying"
}

Use the statement form when the branches perform effects instead of producing a value.

Use for to iterate a sequence, while when a condition controls repetition, and loop for an intentionally unconditional loop:

for name in names {
    Console.WriteLine(name)
}

loop {
    PollDevice()
    Thread.Sleep(1000)
}

Continue with data modeling when values need domain types, or patterns when a decision depends on a value's shape.