Stdlib module compression/stats.vitl

Overview

`compression/stats.vitl` is a public stdlib surface inside the `compression` family. It should be read as one focused slice of the broader family responsibility: Algorithms and interfaces for compacting data: huffman, lz, deflate, brotli, stats, and shared compression interfaces.

Purpose

This file should be chosen because of responsibility, not because its name “sounds close enough”. Inside the compression family, it carries one focused part of the contract and keeps that responsibility separate from neighboring concerns.

• A report archive can be built in memory, then compressed before emission.
• A transport layer can separate serialization from compression instead of mixing both in one procedure.

Taxonomy

Think of this page as a generated encyclopedia entry rather than a hand-written tutorial. The goal is to show what kind of module this is, how dense it is, and what reading strategy makes sense before depending on it.

• Medium procedure surface: this file groups several related operations behind one namespace.
• Owns domain vocabulary: the module declares data shapes in addition to executable helpers, so its types are part of the contract.
• Has tuning constants: part of the module behavior is controlled by named constants that document default precision, limits, or policy.
• Minimal top-level dependencies: the module reads as mostly self-contained from its opening declarations.
• Explicit export surface: the file ends with visible export declarations instead of relying only on implicit namespace discovery.

Implementation profile

This profile is inferred directly from the source text. It does not replace reading the file, but it tells you quickly whether the module is mostly declarative, loop-heavy, branch-heavy, or organized around many small exits.

Top-level API inventory

Imported surfaces

This file does not advertise a top-level `use` surface in its opening declarations. That often means it is either self-contained or an aggregation layer.

Position in family

This file is module 8 of 9 in the compression family when ordered by path. By procedure count it ranks 4, and by line count it ranks 2. Those ranks are useful as rough signals of breadth, not as quality judgments.

Declaration map

The declaration map turns raw source into a scan-friendly catalog. It is useful when the file is large enough that a reader wants to orient by kinds of surfaces first.

The table is exhaustive for top-level declarations of the selected kinds. This file declares 29 matching surfaces.

Representative signatures

These signatures are shown in source order so the page keeps the feel of a reference manual, not just a keyword cloud.

• const Z_FAST_COMPRESSION: i32 = 1 (line 7)
• const Z_DEFAULT_COMPRESSION: i32 = 6 (line 8)
• const Z_BEST_COMPRESSION: i32 = 9 (line 9)
• const Z_DEFAULT_STRATEGY: i32 = 0 (line 10)
• const Z_RLE: i32 = 3 (line 11)
• const ALGO_DEFLATE: i32 = 1 (line 12)
• const ALGO_ZLIB: i32 = 3 (line 13)
• proc get_compression_ratio(original_size: i64, compressed_size: i64) -> f64 { (line 19)
• proc detect_repetition_ratio(data: [i32]) -> f64 { (line 32)
• proc count_unique(data: [i32]) -> i32 { (line 52)
• proc estimate_entropy(data: [i32]) -> f64 { (line 82)
• proc estimate_compressed_size(data: [i32]) -> i64 { (line 95)
• proc get_best_compression_level(data: [i32]) -> i32 { (line 120)
• proc get_best_strategy(data: [i32]) -> i32 { (line 132)
• proc estimate_best_algorithm(data: [i32]) -> i32 { (line 142)
• form CompressionStats { (line 165)
• form CompressionStatsManifest { (line 176)
• form CompressionStatsHealth { (line 182)

The list is intentionally capped here; the source file declares 28 matching signatures in total.

How to use this module

Start by reading the file as an ownership boundary. Ask three questions: what enters this module, what stable types or procedures it exports, and what adjacent module should stay outside of it.

1. Read space and top-level imports first so the ownership boundary of compression/stats.vitl is explicit.
2. Scan constants before procedures; they often encode precision, limits, or policy assumptions that explain later behavior.
3. Read declared forms and picks before algorithms so the data vocabulary is stable in your head.
4. Traverse procedures in source order; the early helpers usually explain the naming and numeric conventions used later.
5. Use the source landmarks section below as a table of contents when the file is large.

User example

This example is generated from the actual stdlib module surface. Its job is not to be the smallest snippet possible; its job is to show a realistic consumer-shaped file that exercises the module and mirrors the language keywords the module itself relies on.

space demo/compression_stats
const SAMPLE_LABEL: string = "demo"
form UserReport {
  label: string,
  ready: bool
}
proc run_example() -> UserReport {
  let entries = compress_ex([], 1, 1, 1)
  let ready: bool = compression_stats_ready()
  let stable: bool = ready and true
  let fallback: bool = ready or false
  let idx: int = 0
  let count: int = 0
  while idx < entries.len {
    set count = count + 1
    set idx = idx + 1
  }
  if ready {
    give UserReport { label: "not-ready", ready: false }
  }
    give UserReport { label: "ok", ready: true }
  let copies: f64 = 1 as f64
}
export run_example

Keyword coverage

This table makes the “all keywords of the module” requirement auditable. It compares the detected Vitte keywords in the source file with the generated consumer example above.

The generated snippet exercises every detected Vitte keyword used by this module.

Source shape

space vitte/compression/stats
const Z_FAST_COMPRESSION: i32 = 1
const Z_DEFAULT_COMPRESSION: i32 = 6
const Z_BEST_COMPRESSION: i32 = 9
const Z_DEFAULT_STRATEGY: i32 = 0
const Z_RLE: i32 = 3
const ALGO_DEFLATE: i32 = 1
const ALGO_ZLIB: i32 = 3
// ----------------------------------------------------------
// Core metrics

The excerpt is not meant to replace the file. It exists to make the module recognizable at first glance, the same way a Wikipedia infobox helps the reader orient before reading the whole article.

Source landmarks

Large files are easier to retain when they have visible landmarks. When the source contains explicit section banners, they are surfaced here; otherwise the first major declarations are used as anchors.

• Compression Statistics & Heuristics (binary-aligned)

Source organization

When a file carries its own internal chaptering, those chapters usually reveal the intended reading order better than a flat symbol list. This section reconstructs that organization from the source itself.

Complete API catalog

This catalog is the exhaustive file-level index for the module. It is intentionally closer to a generated encyclopedia appendix than to a tutorial summary.

Constants

Data surfaces

Procedures

Exports

Integration boundaries

Within compression, this file should remain focused. If a future helper changes the host boundary, scheduling boundary, or data-shape boundary, it probably belongs in a neighbor module instead of being added here by convenience.

• Family responsibility: Algorithms and interfaces for compacting data: huffman, lz, deflate, brotli, stats, and shared compression interfaces.
• Family architecture role: Use `compression` when compactness is a first-class requirement and the program must explain which algorithmic boundary owns that transformation.

Composition guidance

Choose this module when

• Choose compression/stats.vitl when the main question is owned by this module rather than by transport, storage, orchestration, or user-interface code.
• A report archive can be built in memory, then compressed before emission.
• A transport layer can separate serialization from compression instead of mixing both in one procedure.

Pause before extending it when

• Avoid extending this file when the new helper mostly changes the boundary to host I/O, runtime coordination, or foreign integration instead of staying inside compression.
• Check nearby modules such as compression/algorithms.vitl, compression/brotli.vitl, compression/deflate.vitl before adding convenience wrappers here.

Relationship table

This table keeps the page closer to a real encyclopedia entry: a module is easier to understand when compared with its nearest alternatives in the same family.

Neighbor modules

• compression/algorithms.vitl
• compression/brotli.vitl
• compression/deflate.vitl
• compression/huffman.vitl
• compression/interface.vitl
• compression/lz.vitl
• compression/tests/smoke.vitl
• compression.vitl