Defines the options that TypeCheck supports on calls to use TypeCheck.

Supported options:

• :overrides: A list of overrides for remote types. (default: [])
• :default_overrides: A boolean. If false, will not include any of the overrides of the types of Elixir's standard library (c.f. TypeCheck.DefaultOverrides.default_overrides/0). (default: true)
• :enable_runtime_checks: When true, functions that contain a @spec! will be wrapped with a runtime check which will check the input to and result returned from the function. (Default: true).
• :debug: When true, will (at compile-time) print the generated TypeCheck-checking code. (Default: false)

These options are usually specified as passed to use TypeCheck, although they may also be passed in direct calls to TypeCheck.conforms/3 (and its variants).

These options are module-specific and are read/used at compile-time.

setting-different-options-for-different-dependencies

Setting different options for different dependencies

Different default options can be set for each of the different dependencies, by supplying the desired options in the configuration of that dependency under the :type_check key:

config :your_dependency_name, :type_check, [
  enable_runtime_checks: false
  # etc.
]

Note that these values might (by design) be overridden by module-specific options that might be specified at the location where the dependency calls use TypeCheck.

the-supported-options-in-detail

The supported options in detail

overrides

Overrides:

The :overrides field contains a list of remote types to be overridden by a replacement. This is useful to be able to specify TypeCheck-types for types that you do not have control over (because they are for instance defined in a library that is not itself using TypeCheck).

For obvious reasons, using TypeCheck directly should be preferred over overriding types.

Each of the elements in the :overrides list should be written as {original_type, replacement_type}. Both of these can take the shape of either&Module.type/arity or the longer form {Module, :type, arity}.

An example:

use TypeCheck, overrides: [
  {&Ecto.Schema.t/0, &MyProject.TypeCheckOverrides.Ecto.Schema.t/0}
]

enabling-disabling-runtime-checks

Enabling/Disabling runtime checks

By default, runtime checks are enabled.

In the case where the runtime checks turn out to be too slow (for instance, because of working with very large or deeply nested collections) in a particular module, they can be turned off completely.

It is recommended to:

• Only turn them off after benchmarking has shown that this will make a significant difference.
• Only turn them off in e.g. the production environment, keeping them on in the development and test environments.

An example:

use TypeCheck, enable_runtime_checks: Mix.env() != :prod

debugging

Debugging

Passing the option debug: true will at compile-time print the generated code for all added @specs, as well as TypeCheck.conforms/3/TypeCheck.conforms?/3/TypeCheck.conforms!/3 calls.