Docs

Result and option

Produce and match result / option shapes.

Result

A function with an error-return path has a result shape. ! returns the error payload from the current function and leaves the process running. File-scope ! is sem-error-return. ^ v is ok. ! e is err.

/ std/io
/ std/str

$ checked = (x) {
    ? x < 0 {
        ! 'negative'
    }
    ^ x
}

| checked(7) {
    $ value {
        io.print(str.from_int(value))
    }
    ! error {
        io.print(error)
    }
}

Option

An option-shaped function returns ^ v for some and bare ^ for none.

/ std/io
/ std/str

$ maybe = (x) {
    ? x == 0 {
        ^
    }
    ^ x
}

| maybe(7) {
    $ value {
        io.print(str.from_int(value))
    }
    : {
        io.print('empty')
    }
}

Rules

A result match uses $ name for ok and ! name for err. An option match uses $ name for some and : for none. Leaving either shape unhandled is a compile error; there is no silent discard or separate try form.