Reference index

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Tycho language reference

This reference catalogs every feature of the language and how it behaves. Each feature exists to stress-test the arena model in a different dimension — the thesis explains the argument; this reference documents the evidence.

Start with the thesis for why, then come here for what. Every example on every page compiles on both transpilers and produces the shown output.

Pages

Page	Covers
Basics	procedures, parameters (inout), declarations and assignment, expressions and operators, control flow
Types	the scalar types, bytes, string interpolation, distinct type newtypes, bidirectional type inference
Arrays and slices	[T], nested arrays, element places, slices xs[a:b]
Structs and tuples	struct, nested and recursive fields, tuples and multiple return values
Maps	[K: V] for scalar and composite keys, any value type, m[k] as a place
Subscripts	user-defined projections: subscript … -> inout U: yield &<place>, a zero-copy view generalizing &m[k]
Enums, options, and match	sum types, Option(T), Result(T, E), exhaustive match, or_return
Functions and closures	first-class function values, closures, methods (UFCS)
Generics	$T type parameters over functions, structs, and enums
Concurrency	spawn/wait, parallel for, channels, select
FFI	calling C: extern fn, handles, bytes across the boundary
Packages	multi-file packages, import, the corelib
Builtins	the built-in functions, by category

Conventions

• One way to do each thing. Tycho is kept small; where two spellings would do, only one exists. The reference says which.
• Everything is a value. The one idea behind the whole language is that data has value semantics: assignment, arguments, and returns copy, and the copy is deep, so two variables never share storage. Each page says how this plays out for its types instead of restating the principle; the thesis explains the claim and the evidence (no GC, no free, no data races on owned values).
• Examples are real. Every code sample compiles and runs under both the C reference transpiler and the self-hosted transpiler — the language has two implementations that must agree (see The evidence). Output shown in a comment is the actual output.