Maps Postgres type names into Squirrelix's Elixir type metadata and typespecs.

Postgres enums

Custom Postgres enums (kind: "e") map to the internal atom :string and emit String.t() in generated @specs. Runtime encode/decode passes enum labels through as plain strings — Squirrelix does not generate Gleam-style enum ADTs.

JSON and JSONB

JSON columns map to the internal atom :map (shared by json and jsonb) but emit term() in generated @specs. JSON values are not always objects, and Postgrex may return maps, lists, or primitives depending on the stored payload. term() matches Elixir 1.20 practice for dynamically typed JSON columns; row result maps still use map() with required/1 keys via row_typespec/1.

Composite types

Postgres composite types (kind: "c", including create type ... as (...)) are intentionally unsupported. Squirrelix rejects them with an UnsupportedPostgresType error and an actionable hint (select individual fields, or cast to json/jsonb/text). This matches Gleam Squirrel and keeps generated Elixir APIs limited to stdlib typespecs and flat row maps — no nested composite modules or opaque encodings.

Unsupported types

Postgres range/multirange types and several other built-ins are intentionally unsupported. Inference returns UnsupportedPostgresType with an actionable hint (for example: select bounds as separate columns, or cast to text / jsonb in SQL). See the Types guide for the full inventory.