XCX 3.0 — Changelog (2.2 → 3.0)

April 2026 · Type: ANNOUNCEMENT

Note: XCX 3.0 may contain bugs — the VM architecture has grown complex over time. Please report issues. XCX 4.0 is planned with a fully redesigned architecture.

Database (NEW)

Entirely new subsystem. No equivalent existed in 2.2.

• [NEW] database: block — declares a SQLite connection with engine, path, timeout, readonly fields
• [NEW] Connections are lazy — opened on first use; SQLite creates the file automatically
• [NEW] Multiple simultaneous connections supported
• [NEW] Column attributes for table: declarations used by the DB module: @pk, @unique, @optional, @default(v), @fk(t.col) — @auto already existed in 2.2
• [NEW] Write operations: db.push(), db.save() (upsert, requires @pk), db.insert()
• [NEW] Read operations: db.fetch(), db.fetch().where() (compiles to SQL WHERE), db.query(), db.queryRaw(), .first() on raw results
• [NEW] Delete operations: db.remove().where() (.where() required — compile error D401 otherwise), db.truncate(), db.exec()
• [NEW] Transactions: db.begin(), db.commit(), db.rollback() — auto rollback on halt.error
• [NEW] Result capture via as: returns object with affected and insertId fields
• [NEW] DDL: db.sync(), db.drop(), db.has()
• [NEW] @optional columns: SQL NULL maps to the XCX type’s default value on read (0, 0.0, '', false)
• [NEW] save() without @pk = compile error; remove() without .where() = compile error (D401)
• [NEW] Workaround documented for fiber-local variable scoping bug on Windows (planned fix in 4.0)

Named Arguments (NEW)

• [NEW] table.add(), table.insert(), and db.insert() now accept arguments by column name
• [NEW] Positional and named arguments can be mixed — positional must come first
• [NEW] @auto columns cannot be passed explicitly (compile error)
• [NEW] Duplicate column names in one call = compile error
• [NEW] Namespace separation: left side of = is the column name, right side is a local expression — no conflict

Type System

• [NEW] Type aliases added to simple types table: i / int, f / float, s / str, b / bool
• [NEW] array:json — array of JSON objects, documented as a distinct type
• [NEW] database: added as a complex type
• [CHG] Strict collection validation — type mismatches in array/set/table literals are now compile errors (e.g. array:s: names {\"Alice\", 2} → ERROR [S103])
• [INT] Internal “Other” type removed from the type checker

Error System (NEW)

No structured error codes existed in 2.2.

• [NEW] Sxxx / Dxxx error code series, consistent across REPL and compiler:

Collections — Arrays

• [NEW] .toStr() — serializes array to a JSON-formatted string
• [NEW] .toJson() — converts array to a native json value

Collections — Maps

• [NEW] .toStr() — serializes map to a JSON-formatted string
• [NEW] .toJson() — serializes map to a JSON object; keys converted to strings

Collections — Tables

• [NEW] .toJson() — serializes all rows to a JSON array of objects; @auto columns included
• [NEW] Named arguments for .add() and .insert() (see Named Arguments section)
• [NEW] Column attributes @pk, @unique, @optional, @default(v), @fk(t.col) — used when connecting a table to a database
• [CHG] Stricter row and column validation

Collections — Sets / random.choice

• [CHG] random.choice from now works on both sets and arrays — in 2.2 it was restricted to sets only
• [CHG] Picking from an empty set or array now returns false (previously undocumented)

Standard Library — crypto

• [NEW] crypto.hash(data, "base64_encode") — encodes to Base64
• [NEW] crypto.hash(data, "base64_decode") — decodes from Base64

Standard Library — store

• [NEW] store.list(p) — lists files and folders at path
• [NEW] store.isDir(p) — checks if path is a directory
• [NEW] store.size(p) — returns file size in bytes
• [NEW] store.mkdir(p) — creates directory recursively
• [NEW] store.glob(pat) — returns files matching a glob pattern
• [NEW] store.zip(src, target) — archives to zip
• [NEW] store.unzip(zip, dest) — extracts zip

Standard Library — random

• [NEW] random.int(min, max) / random.int(min, max @step n) — random integer in range
• [NEW] random.float(min, max) / random.float(min, max @step n) — random float in range
• [CHG] random.choice from now supports arrays in addition to sets (see Collections — Sets)

Terminal & Input

• [NEW] input module: input.key(), input.key() @wait, input.ready()
• [NEW] Full set of key constants: "UP", "DOWN", "LEFT", "RIGHT", "ENTER", "ESC", "BACKSPACE", "TAB", "F1"–"F12", "KEY_CTRL_C", "KEY_CTRL_Z", "KEY_CTRL_S"
• [NEW] .terminal !raw — raw mode (no echo, no buffering)
• [NEW] .terminal !normal — restores normal terminal mode
• [NEW] .terminal !cursor on / .terminal !cursor off
• [NEW] .terminal !move x y — moves cursor to position
• [NEW] .terminal !write expr — prints without trailing newline
• [CHG] 2.2 had only 3 terminal directives (!clear, !exit, !run); 3.0 adds 6 more

I/O — User Input (>?)

• [CHG] In 2.2, entering a value of the wrong type caused the variable’s type to change at runtime (dynamic typing). In 3.0 this behavior is removed — >? strictly attempts to parse into the declared type.

JSON

• [NEW] .push(val) — appends a json element to a JSON array node; halt.error if called on an object
• [NEW] .first() — returns the first element of a JSON array; halt.error if empty
• [NEW] .toStr() — renamed from .to_str() (see Breaking Changes)
• [NEW] Serialization from collections: .toJson() available on maps and tables, producing JSON objects and arrays respectively

HTTP — Response Object

2.2 response had four fields. 3.0 adds two:

• [NEW] text — raw response body as a string (always available)
• [NEW] error — error message string on request failure; empty string if OK

HTTP — CORS

• [CHG] Behavior changed from 2.2 to 3.0:
  • 2.2: Engine added Access-Control-Allow-Origin: * automatically; manually adding it caused a browser duplicate header error
  • 3.0: Engine adds CORS headers only if they are missing from the response; explicitly declaring them in code is now recommended

String Methods

• [NEW] .split(separator) — splits string by separator, returns array:s

PAX Package Manager

project.pax

• [NEW] version field — semantic version (e.g. "1.0.0")
• [NEW] author field — synced with registry
• [NEW] description field
• [NEW] main field — custom entry point (default: src/main.xcx)
• [NEW] tags field — list of strings for registry discoverability
• [NEW] Version pinning in deps: "mathlib@1.2.0"

Commands

• [NEW] xcx pax clone <name> — clones the entire package repository
• [NEW] xcx pax login <token> — saves API token for publishing
• [NEW] xcx pax logout — clears stored session
• [NEW] xcx pax whoami — verifies registry account
• [NEW] xcx pax publish — pushes project manifest to the registry

Lockfile

• [NEW] pax.lock — deterministic builds; locks all dependencies to specific versions and sources; should be committed to version control

Breaking Changes

Internal Changes

• [INT] Type checker refactor
• [INT] Removal of internal “Other” type
• [INT] Internal VM structures documented
• [INT] Readable errors in REPL
• [INT] Compilation timing output
• [INT] Improved diagnostics