0004

Status: Accepted

Context

Lua tables cannot hold nil values: assigning nil removes the key. If the prelude defines unit = nil, an Array Unit collapses to an empty table and a length check silently returns 0.

Decision

unit is {} (an empty table), never nil. This requires purescript-lua/purescript-lua-prelude v7.2.0 or newer.

Consequences

• Array Unit keeps its length.
• If eval goldens for unit arrays start printing 0, a package set has downgraded the prelude below v7.2.0. Do not accept such goldens.