Use for Luau language semantics, tables, control flow, string patterns, scope, closures, and cross-language translation errors.

Luau Core Language When to Load Load for pure Luau syntax and semantics: truthiness, tables, iteration, functions, scope, operators, string patterns, and ports from JavaScript or Python. Use roblox luau types for type annotations, roblox luau patterns for ownership and lifecycle, and domain skills for Roblox APIs. Quick Reference Only false and nil are falsy. 0 , "" , and {} are truthy. Equality does not coerce types. 0 == "0" is false. Inequality is ~= . Array conventions are 1 based. array is meaningful only for a sequence without nil gaps. Assigning nil removes a table key. Assigning a table copies the reference. table.clone is shallow. Dictionary iteration order is unspecified. Do not make behavior depend on it. Dynamic keys require brackets: record[field] . Dot syntax uses a literal identifier. Missing arguments become nil ; extra results and arguments can be discarded by context. Prefer an if expression over condition and a or b when a may be false or nil . Local names are scoped from their declaration onward. Forward declare mutually recursive functions. Luau string patterns are not regular expressions. Their syntax and capabilities differ. Backtick interpolation and .. concatenation are both valid. Choose the clearer form; collect many fragments and join once in a hot loop. NaN does not equal itself and defeats < / comparisons; test with x ~= x . Binary data uses the buffer library: fixed size, 0 based offsets, explicit width reads/writes. Avoid buffer.readinteger / writeinteger (stubs only, not released runtime). For Base64, hashing, or compression use EncodingService (buffers, not strings; JSON still via HttpService ). Details: see full reference. Translation traps JavaScript === , !== , null , optional chaining, spread, arrow functions, and array methods are not Luau syntax. Python None , zero based list assumptions, list comprehensions, exceptions, and implicit tuple behavior do not translate directly. x or fallback tests truthiness, not only absence. It replaces a valid false value. typeof(value) recognizes Roblox datatypes; type(value) reports the underlying Luau type category. Review Valid Luau, no nil gaps in sequences, no assumed dictionary order, no accidental aliases, no cross language syntax, no boolean expressions hiding false or nil . Detailed language traps and translation examples: [references/full.md](references/full.md)

roblox-luau-core