Changelog

All notable changes to this project are documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

0.2.0 - 2026-09-24

Changed

• The generated functions assemble the struct as a single literal that names every field, where they used to call struct/2, Map.update!/3 and Enum.reduce/3. Those take a field name as a runtime value and hand back a bare struct(), so dialyzer could see neither the module nor any field type through them, and every generated @spec was a promise it took on faith rather than one it checked. The assembled struct is also carried through validate/1, which is specced to take t(), so a field copied from the struct in hand keeps its declared type instead of reading as any().
• validate/1 is generated as @spec validate(t()) :: :ok for a struct that declares no validators, since there is nothing it could report. On such a struct put/2, put!/2, update/2 and update!/2 are typed as {:ok, t()} and have nothing to raise, and new/1 keeps its error half for as long as a key can be missing from the attributes it is given. Matching on {:error, reasons} from any of them is then a clause the compiler reports as unreachable.
• update/2 applies its functions in field declaration order rather than the order the updates map happens to iterate in. Each function still receives the value its own field held before the update, so this is only visible to functions with side effects.
• Together these cut the work per call considerably: on an eight-field struct with two validators, new/1 went from 268ns to 58ns given every field, and from 87ns to 45ns given only the two enforced ones. One struct is allocated per call rather than one per field written, and a passing validate/1 now allocates nothing.

Removed

• The runtime rejection of a key the struct does not declare. Such a key is not in the generated argument types, so dialyzer reports it at the line that writes it, and paying for the same answer again on every call is work the types already did. A key that reaches a generated function anyway is ignored, where it used to come back as {:error, ["unknown key(s): ..."]}.

  This is the one change here that can break a caller: code matching on that error, or relying on an undeclared key being refused at runtime, no longer gets it. A missing enforced key is still reported as before.

0.1.0 - 2026-09-22

Initial release.

• plugin TypedStructBuilderValidators generates new/1, new!/1, validate/1, put/2, put!/2, update/2 and update!/2 on a typedstruct block, each with a @spec built from the declared field types.
• validator/1 and validator/2 declare predicates on the completed struct, inlined into validate/1, with the predicate's source as the default failure message.
• :only narrows the generated set; passing a default name as an option renames that function.
• :fields_type_name, :changes_type_name and :updates_type_name declare named types for the generated argument maps.