# TypeResolver
[](https://hex.pm/packages/type-resolver)
Type resolver is a library to resolve spec-types at compile time.
That is, reducing the specs to only native types by resolving user-defined,
built-in and remote types. The result is a type expressed in easy to
handle structs of types.
## Rationale
Often times we want to analyse spec-types in macros and derive functionality
from these types. Analysing and working with AST from `Code.Typespec` or
Erlang AST is challenging and cumbersome. Furthermore, there is no
standalone library that resolves user-defined types, built-in types and
remote-types. This library fills this gap.
## Usage
The library offers the macro `TypeResolver.resolve/1` that can be used
as follows:
```elixir
TypeResolver.resolve(integer() | String.t())
```
It returns the following representation:
```elixir
%TypeResolver.UnionT{
inner: [%TypeResolver.Types.IntegerT{}, %TypeResolver.Types.BinaryT{}]
}
```
## Type exporter
To resolve remote types, we rely on `Code.Typespec.fetch_types/1`. For
this function to work, the module has to be compiled into a beam file,
which cannot always be ensured at macro expansion time.
To handle this problem, we provide the module `TypeResolver.TypeExporter`.
This module takes care of types being exported and makes them available
at macro expansion time.
## Limitations
- Currently this library cannot handle recursive types and does not detect
them. When using recursive times, compilation will be stuck in an infinite
recursion.
- Struct types don't get their member resolved
## Installation
If [available in Hex](https://hex.pm/docs/publish), the package can be installed
by adding `type_resolver` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:type_resolver, "~> 0.1.0"}
]
end
```
Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
be found at <https://hexdocs.pm/type_resolver>.
## License
Copyright © 2024 Bravobike GmbH and Contributors
This project is licensed under the Apache 2.0 license.
