View Source Dune.Session (dune v0.3.8)

Sessions provide a way to evaluate code and keep state (bindings, modules...) between evaluations.

Dune.Session could be used to implement something like a safe IEx shell, or to compile a module once and call it several times without the overhead of parsing.

Dune.Session is also a struct that is used to store the state of an evaluation.

Only the following fields are public:

  • last_result: contains the result of the last evaluation, or nil for empty sessions

Other fields are private and shouldn't be accessed directly.

Summary

Functions

Evaluates the provided string in the context of the session and returns a new session.

Returns a new empty session.

Types

@opaque private_compile_env()
@opaque private_env()
@type t() :: %Dune.Session{
  bindings: keyword(),
  compile_env: private_compile_env(),
  env: private_env(),
  last_result: nil | Dune.Success.t() | Dune.Failure.t()
}

The type of a Dune.Session.

Functions

Link to this function

eval_string(session, string, opts \\ [])

View Source
@spec eval_string(t(), String.t(), keyword()) :: t()

Evaluates the provided string in the context of the session and returns a new session.

The result will be available in the last_result key. In case of a success, the variable bindings or created modules will be saved in the session. In case of a failure, the rest of the session state won't be updated, so it is possible to keep executing instructions after a failure

Examples

iex> Dune.Session.new()
...> |> Dune.Session.eval_string("x = 1")
...> |> Dune.Session.eval_string("x + 2")
#Dune.Session<last_result: %Dune.Success{value: 3, inspected: "3", stdio: ""}, ...>

iex> Dune.Session.new()
...> |> Dune.Session.eval_string("x = 1")
...> |> Dune.Session.eval_string("x = x / 0")  # will fail, but the previous state is kept
...> |> Dune.Session.eval_string("x + 2")
#Dune.Session<last_result: %Dune.Success{value: 3, inspected: "3", stdio: ""}, ...>
@spec new() :: t()

Returns a new empty session.

Examples

iex> Dune.Session.new()
#Dune.Session<last_result: nil, ...>