Modules and tests

sub init makes a small project:

main.sub
lib/text.sub

needs [ clock ]

use "./lib/text.sub"

let started = now()
print(greet("world"))
print(shout("subtype"))
print("took", now() - started >= 0)

test "greet says hello" {
  assert_eq(greet("sub"), "hello, sub")
}

fn greet(name: String) -> String {
  "hello, {name}"
}

fn shout(text: String) -> String {
  upper(text) + "!"
}

test "shout makes it loud" {
  assert_eq(shout("hi"), "HI!")
}

The subtype rule across files

A library function that touches the outside says so with its own needs. The script that calls it must allow that. A call that needs more than the script holds is an error, with the file and the line:

fn load(p: Path) needs [read [p]] -> String { read(p) or "" }

Tests

sub test main.sub --yes

ok      greet says hello
ok      shout makes it loud
2 passed, 0 failed

Test blocks live next to the code they test, in the script or a library. sub test runs on the interpreter, not on Wasmtime.