First program

Write a small file, run it and check its result before introducing custom syntax or application libraries.

Create a source file

Save the following as hello.rl:

const greeting = "Hello, RecurLoop"
var answer = 6 * 7
print greeting
print answer
assert answer == 42

Run and verify

recurloop --file hello.rl

The program prints a greeting and 42. A failed assertion reports a problem and causes the run to fail. The embedded standard language is available without a separate bootstrap step.

Introduce a function

let double = fn (value:i64) -> i64 { return value * 2 }
assert double(21) == 42

i64 is a signed native integer type. Functions compile to native code and can be called from ordinary expressions.

Find help while reading code

recurloop --docs search "function"
recurloop --docs search "ownership" --json

Search finds public language and package documentation. The --json form is useful for tools. Continue through Values, Control flow and Functions, or use the Learning path to see the full sequence.