First checked and executed program

Prerequisite

Use a Topaz distribution that provides language mode 5.21 and the default SELF compiler.

1. Write a function

Save the source in the check example below as first-program.tpz. The function returns a greeting. The final call sends it to std.io.writeLine. This example uses an explicit output operation; it does not depend on automatic printing of a top-level value.

2. Check the program

Link

Check the first program

Link

check · checking · Verification: passed

first-program.tpzCheck the first programOpen in Playground

import std.io
function greet(name: string) -> string {
return "Hello, {name}!"
}
io.writeLine(greet("Topaz"))

Recorded outputexit 0

first-program.tpz: types-ok (2 modules)
first-program.tpz: resolve-ok (2 modules)

$ topaz check first-program.tpz --compiler self · recorded with topaz 5.21.3

Expected result

Checking accepts the program. Exit code 0.

Observed assertions · passed · 5.21.3

2026-11-06T04:37:26.2102809Z · checking · sha256:b6c3f574b78c558b526196fa04f5d835c9fe1df59d07397dbf4e5d279a3e1665

Exit code 0.

Observed stdout

first-program.tpz: types-ok (2 modules)
first-program.tpz: resolve-ok (2 modules)

No stderr.

Passed · expected 0; observed 0

Observed assertions · passed · 5.21.3

2026-11-06T13:40:27.7737018Z · checking · sha256:b6c3f574b78c558b526196fa04f5d835c9fe1df59d07397dbf4e5d279a3e1665

Exit code 0.

Observed stdout

first-program.tpz: types-ok (2 modules)
first-program.tpz: resolve-ok (2 modules)

No stderr.

Passed · expected 0; observed 0

Source evidence

document docs/npm/README.md at d61f9fd0efb0 · 48-79
implementation source compiler/crates/topaz_cli/src/command/dispatch.rs at d61f9fd0efb0 · 86-128
implementation source compiler/crates/topaz_resolve/src/std/521/io.tpz at d61f9fd0efb0 · 3-5

Expected result: checking succeeds. This step checks the program without running its output operation. If checking fails, follow the reported diagnostic code to Diagnostics. The check reference defines input, options, and output channels.

3. Run the program

Link

Run the first program

Link

run · runtime · Verification: passed

first-program.tpzRun the first programOpen in Playground

import std.io
function greet(name: string) -> string {
return "Hello, {name}!"
}
io.writeLine(greet("Topaz"))

Recorded outputexit 0

Hello, Topaz!

$ topaz run first-program.tpz --compiler self · recorded with topaz 5.21.3

Expected result

Execution completes. Exit code 0.

No stderr.

Expected stdout

Hello, Topaz!

Observed assertions · passed · 5.21.3

2026-11-06T04:37:26.2811132Z · runtime · sha256:b6c3f574b78c558b526196fa04f5d835c9fe1df59d07397dbf4e5d279a3e1665

Exit code 0.

Observed stdout

Hello, Topaz!

No stderr.

Passed · expected 0; observed 0
Passed · stdout matches the authored expectation
Passed · stderr matches the authored expectation

Observed assertions · passed · 5.21.3

2026-11-06T13:40:27.8470673Z · runtime · sha256:b6c3f574b78c558b526196fa04f5d835c9fe1df59d07397dbf4e5d279a3e1665

Exit code 0.

Observed stdout

Hello, Topaz!

No stderr.

Passed · expected 0; observed 0
Passed · stdout matches the authored expectation
Passed · stderr matches the authored expectation

Source evidence

document docs/npm/README.md at d61f9fd0efb0 · 48-79
implementation source compiler/crates/topaz_cli/src/command/dispatch.rs at d61f9fd0efb0 · 137-153
implementation source compiler/crates/topaz_resolve/src/std/521/io.tpz at d61f9fd0efb0 · 3-5
implementation source compiler/crates/topaz_self_frontend/topaz/emitter/builtins.tpz at d61f9fd0efb0 · 32-40
implementation source compiler/crates/topaz_value/src/value/runtime.rs at d61f9fd0efb0 · 634-654

The run command checks the selected unit before execution. The expected program output is shown above; an observation is displayed after the exact source is executed.

Verification

Link

Public Topaz 5.21.3 checked and ran this program successfully in Docs run 42224592687, attempt 2. Both commands exited with code 0, and run printed the expected greeting. The new receipts preserve the observed output from the unchanged fixture and invocation. The earlier receipts remain available.