t81-foundation

T81Lang Standard Library Reference

Date: 2026-02-26
Status: Active
Scope: Current lang/stdlib/std/*.t81 module surface

1. Read This First

This reference describes currently available std.* modules and usage patterns.

• Promotion status and determinism posture are tracked in:
  • docs/status/STDLIB_PROMOTION_SNAPSHOT_2026-03.md
• Change governance is defined in:
  • docs/governance/STDLIB_CHANGE_POLICY.md
• Canonical module descriptions remain in:
  • docs/standards/standard-library.md

2. How to Use Modules

Example import and use:

fn main() -> i32 {
    let txt: T81String = "hello";
    let n: i32 = std.text.str_len(txt);
    print(n);
    return 0;
}

Guidance:

1. Prefer explicit std.<module>.<function> calls.
2. Treat bounded and experimental modules as non-frozen surfaces.
3. For deterministic behavior checks, mirror fixture patterns under tests/fixtures/t81lang_std_*.

3. Module Index

Module	Status	Core Usage	Evidence Fixture/Test
std.core	bounded	assert, debug, unwrap_or	tests/cpp/cli_std_core_fixtures_test.cpp
std.math	bounded	sqrt, exp, pow, clamp and related math aliases	tests/cpp/cli_std_math_fixtures_test.cpp
std.io	bounded	println, print_int, print_float, stream, net	tests/cpp/cli_std_runtime_fixtures_test.cpp
std.collections	stable	vector/list/map/set/tree/graph staged deterministic helpers	tests/cpp/cli_std_collections_fixtures_test.cpp
std.text	stable	str_len, concat, split, join, replace	tests/cpp/cli_std_text_fixtures_test.cpp
std.bytes	stable	bytes len, concat, split, join, conversions	tests/cpp/cli_std_bytes_fixtures_test.cpp
std.symbol	stable	intern, to_string, eq, ne	tests/cpp/cli_std_symbol_fixtures_test.cpp
std.sys	bounded	exit, time, entropy, proof, reflect	tests/cpp/cli_std_runtime_fixtures_test.cpp
std.async	bounded	yield, sleep, thread, promise	tests/cpp/cli_std_runtime_fixtures_test.cpp
std.tensor	bounded	load, from_list, vec_add, matmul	tests/cpp/cli_std_tensor_fixtures_test.cpp
std.agent	experimental	self_reflect	tests/cpp/cli_std_runtime_fixtures_test.cpp

4. Determinism Notes

1. Determinism guarantees are bounded by DCP/registry-verified surfaces.
2. std.math is bounded due to host-math dependence for transcendental paths.
3. std.sys and std.async are deterministic placeholder aliases on current profile.
4. std.agent remains experimental and must not be treated as a frozen contract.

5. Fixture-Driven Usage References

Use these as executable examples:

• tests/fixtures/t81lang_std_core/
• tests/fixtures/t81lang_std_math/
• tests/fixtures/t81lang_std_text/
• tests/fixtures/t81lang_std_bytes/
• tests/fixtures/t81lang_std_collections/
• tests/fixtures/t81lang_std_tensor/
• tests/fixtures/t81lang_std_runtime/
• tests/fixtures/t81lang_std_symbol/

6. Upgrade Discipline

Before relying on a symbol as stable:

1. Check its module status in STDLIB_PROMOTION_SNAPSHOT_2026-03.md.
2. Confirm fixture and test evidence exists.
3. Confirm no conflicting change-class record in STDLIB_CHANGE_POLICY.md.

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