# Landin

> One systems language from a 32 KB microcontroller to a hosted application. Manual memory with arenas as the idiom and no garbage collector, reference counting or destructors; separate reference permission and binding mutability; local origin and escape analysis rather than a borrow checker; concepts with evidence tables for both static generics and runtime dispatch; no compile-time execution and no macros. Three native backends emit assembly for Linux x86-64, Darwin arm64 and Cortex-M0.

Specification 0.2.8. Deliberately partial: it says what is true today rather
than what is intended, and it grows one slice at a time. There is no
package acquisition story yet, and no claim of memory or
resource safety — the language is deliberately unsafe with useful local
checks. Read llms-full.txt before writing a program: the compiler enables
a kernel narrower than the tour describes, and refuses the difference by
name.

## Writing Landin

- [Library reference](https://www.701.dev/library.html): public API signatures, contracts, module overviews and executable examples. The searchable inventory is [library-index.json](https://www.701.dev/library-index.json).
- [Installing](https://www.701.dev/readme.html#installing): the nix routes, where a release archive unpacks and what `refine version` prints.
- [The primer](https://www.701.dev/llms-primer.txt): start here. Generated from the compiler's own tables — how to install, compile and run, the kernel's vocabulary, its grammar in one piece, every spelling the compiler refuses by name, and every diagnostic code. 33 KB.
- [the tour](https://www.701.dev/tour.html): the language explained construct by numbered construct, teaching by example. Teaches; does not decide.
- [running examples](https://www.701.dev/examples.html): eleven complete programs the compiler emits and the gates run. Each is known to compile and run, so each is safe to copy from.

## Deciding what is legal

- [the specification](https://www.701.dev/spec.html): normative. The grammar of the enabled kernel, the rules the tour leaves unsaid, and every decision with its alternative and the fixture that pins it.
- [how the documents are arranged](https://www.701.dev/documents.html): which of the two documents holds which kind of rule, and where a new one goes. Read it before citing either.
- [the fixtures](https://www.701.dev/fixtures.html): the fixture corpus: what the compiler is held to accept and refuse, and the format that outlives the implementation checking it.

## Optional

- [Everything in one file](https://www.701.dev/llms-full.txt): the primer above, then the tour, the specification and the worked programs in full. 1.7 MB, most of it the register of decisions, which says why a rule is what it is rather than what to write.
- [the design, in one page](https://www.701.dev/handoff.html): the design in one page, and which decisions must not be quietly reversed.
- [the roadmap](https://www.701.dev/roadmap.html): the sole authority for open work: its phases, their items and gates, and the register.
- [the intermediate representation](https://www.701.dev/ir.html): how checked source becomes verified target-neutral IR.
- [target contracts](https://www.701.dev/targets.html): target descriptions, ABI capabilities and backend boundaries.
- [editor and IDE support](https://www.701.dev/editors.html): installable highlighting for the major editor families.