View Source DSL: Reactor.Dsl

reactor

The top-level reactor DSL

Nested DSLs

• middlewares
  • middleware
• around
  • argument
  • wait_for
• collect
  • argument
  • wait_for
• compose
  • argument
  • wait_for
• debug
  • argument
  • wait_for
• flunk
  • argument
  • wait_for
• group
  • argument
  • wait_for
• input
• map
  • argument
  • wait_for
• step
  • argument
  • wait_for
• switch

  • matches?

  • default

Options

Name	Type	Default	Docs
return	atom		Specify which step result to return upon completion.

reactor.middlewares

Middleware to be added to the Reactor

Nested DSLs

• middleware

reactor.middlewares.middleware

middleware module

Name a middleware to be added to the Reactor.

Arguments

Name	Type	Default	Docs
module	module		The middleware to be added to the Reactor.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the middleware.

Introspection

Target: Reactor.Dsl.Middleware

reactor.around

around name, fun \\ nil

Wrap a function around a group of steps.

Nested DSLs

• argument
• wait_for

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the group of steps.
fun	(any, any, any, any -> any) | mfa		The around function. See Reactor.Step.Around for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the step.
allow_async?	boolean	false	Whether the emitted steps should be allowed to run asynchronously.

reactor.around.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.around.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Around

reactor.collect

collect name

A Reactor step which simply collects and returns it's arguments.

Arguments can optionally be transformed before returning.

Nested DSLs

• argument
• wait_for

Examples

collect :latest_release_uri do
  argument :repository, input(:repository)
  argument :organisation, input(:organisation)

  transform fn inputs ->
    %{uri: "https://api.github.com/repos/#{inputs.organisation}/#{inputs.repository}/releases/latest"}
  end
end

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the step. Used when choosing the return value of the Reactor and for arguments into other steps.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the step.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the entire argument map before it is returned.

reactor.collect.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.collect.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Collect

reactor.compose

compose name, reactor

Compose another Reactor into this one.

Allows place another Reactor into this one as if it were a single step.

Nested DSLs

• argument
• wait_for

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the step. Allows the result of the composed reactor to be depended upon by steps in this reactor.
reactor	Reactor | module		The reactor module or struct to compose upon.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the step.

reactor.compose.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.compose.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Compose

reactor.debug

debug name

Inserts a step which will send debug information to the Logger.

Nested DSLs

• argument
• wait_for

Examples

debug :debug do
  argument :suss, result(:suss_step)
end

Arguments

Name	Type	Default	Docs
name	atom		A unique identifier for the step.

Options

Name	Type	Default	Docs
level	:emergency | :alert | :critical | :error | :warning | :notice | :info | :debug	:debug	The log level to send the debug information to.

reactor.debug.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.debug.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Debug

reactor.flunk

flunk name, message

Creates a step which will always cause the Reactor to exit with an error.

This step will flunk with a Reactor.Error.Invalid.ForcedFailureError with it's message set to the provided message. Additionally, any arguments to the step will be stored in the exception under the arguments key.

Nested DSLs

• argument
• wait_for

Examples

flunk :outaroad, "Ran out of road before reaching 88Mph"

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the step. Used when choosing the return value of the Reactor and for arguments into other steps.
message	nil | String.t | Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		The message to to attach to the exception.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the step.

reactor.flunk.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.flunk.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Flunk

reactor.group

group name

Call functions before and after a group of steps.

Nested DSLs

• argument
• wait_for

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the group of steps.

Options

Name	Type	Default	Docs
before_all	(any, any, any -> any) | mfa		The before function. See Reactor.Step.Group for more information.
after_all	(any -> any) | mfa		The after function. See Reactor.Step.Group for more information.
allow_async?	boolean	true	Whether the emitted steps should be allowed to run asynchronously.
description	String.t		An optional description for the step.

reactor.group.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.group.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Group

reactor.input

input name

Specifies an input to the Reactor.

An input is a value passed in to the Reactor when executing. If a Reactor were a function, these would be it's arguments.

Inputs can be transformed with an arbitrary function before being passed to any steps.

Examples

input :name

input :age do
  transform &String.to_integer/1
end

Arguments

Name	Type	Default	Docs
name	atom		A unique name for this input. Used to allow steps to depend on it.

Options

Name	Type	Default	Docs
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the input before it is passed to any steps.
description	String.t		An optional description for the input.

Introspection

Target: Reactor.Dsl.Input

reactor.map

map name

Execute nested steps for every item of an iterator.

Allows you to "map over" a collection applying a some steps to each element, returning a list of new values. The input collection must be bounded - ie you cannot pass infinite streams into this step or it will just loop forever - and because it has to keep the results from each batch will eventually just use up all available RAM.

Under the hood we use Iter to handle lazy iteration of the collection. This means that you can pass an Iter.t or any value for which Iter.IntoIterable is implemented.

A note on ordering

If your application doesn't need the results back in the same order that they were provided then setting strict_ordering? to false will increase performance - especially on large input sets.

Nested DSLs

• argument
• wait_for

Examples

map :double_numbers do
  input input(:numbers)

  step :double do
    argument :number, element(:double_numbers)

    run fn %{number: number}, _ ->
      {:ok, number * 2}
    end
  end
end

step :get_subscriptions do
  run fn _, _ ->
    Stripe.Subscription.list()
  end
end

map :cancel_subscriptions do
  input result(:get_subscriptions)

  step :cancel do
    argument :sub_id, element(:cancel_subscriptions, [:id])

    run fn args, _ ->
      Stripe.Subscription.cancel(arg.sub_id, %{prorate: true, invoice_now: true})
    end
  end

  return :cancel
end

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the step.

Options

Name	Type	Default	Docs
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		The iterator or enumerable to use as the source of the iteration.
allow_async?	boolean	false	Whether the emitted steps should be allowed to run asynchronously.
batch_size	pos_integer	100	The number of items to consume off the source when emitting steps.
description	String.t		An optional description for the step.
return	atom		The name of the nested step to use as the return value.
strict_ordering?	boolean	true	Whether the mapped values must be returned in the same order that they were provided.

reactor.map.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.map.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Map

reactor.step

step name, impl \\ nil

Specifies a Reactor step.

Steps are the unit of work in a Reactor. Reactor will calculate the dependencies graph between the steps and execute as many as it can in each iteration.

See the Reactor.Step behaviour for more information.

Nested DSLs

• argument
• wait_for

Examples

step :create_user, MyApp.Steps.CreateUser do
  argument :username, input(:username)
  argument :password_hash, result(:hash_password)
end

step :hash_password do
  argument :password, input(:password)

  run fn %{password: password}, _ ->
    {:ok, Bcrypt.hash_pwd_salt(password)}
  end
end

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the step. Used when choosing the return value of the Reactor and for arguments into other steps.
impl	module | nil		A module that implements the Reactor.Step behaviour that provides the implementation.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the step.
run	(any -> any) | mfa | (any, any -> any) | mfa		Provide an anonymous function which implements a run/1-2 callback. Cannot be provided at the same time as the impl argument.
undo	(any -> any) | mfa | (any, any -> any) | mfa | (any, any, any -> any) | mfa		Provide an anonymous function which implements a undo/1-3 callback. Cannot be provided at the same time as the impl argument.
compensate	(any -> any) | mfa | (any, any -> any) | mfa | (any, any, any -> any) | mfa		Provide an anonymous function which implements a compensate/1-3 callback. Cannot be provided at the same time as the impl argument.
max_retries	:infinity | non_neg_integer	:infinity	The maximum number of times that the step can be retried before failing. Only used when the result of the compensate callback is :retry.
async?	boolean	true	When set to true the step will be executed asynchronously via Reactor's TaskSupervisor.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the entire argument map before it is passed to the step.

reactor.step.argument

argument name, source \\ nil

Specifies an argument to a Reactor step.

Each argument is a value which is either the result of another step, or an input value.

Individual arguments can be transformed with an arbitrary function before being passed to any steps.

Examples

argument :name, input(:name)

argument :year, input(:date, [:year])

argument :user, result(:create_user)

argument :user_id, result(:create_user) do
  transform & &1.id
end

argument :user_id, result(:create_user, [:id])

argument :three, value(3)

Arguments

Name	Type	Default	Docs
name	atom		The name of the argument which will be used as the key in the arguments map passed to the implementation.
source	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		What to use as the source of the argument. See Reactor.Dsl.Argument for more information.

Options

Name	Type	Default	Docs
description	String.t		An optional description for the argument.
transform	(any -> any) | module | nil		An optional transformation function which can be used to modify the argument before it is passed to the step.

Introspection

Target: Reactor.Dsl.Argument

reactor.step.wait_for

wait_for names

Wait for the named step to complete before allowing this one to start.

Desugars to argument :_, result(step_to_wait_for)

Examples

wait_for :create_user

Arguments

Name	Type	Default	Docs
names	atom | list(atom)		The name of the step to wait for.

Options

Name	Type	Default	Docs
description	String.t		An optional description.

Introspection

Target: Reactor.Dsl.WaitFor

Introspection

Target: Reactor.Dsl.Step

reactor.switch

switch name

Use a predicate to determine which steps should be executed.

Nested DSLs

• matches?

• default

Arguments

Name	Type	Default	Docs
name	atom		A unique name for the switch.

Options

Name	Type	Default	Docs
on	Reactor.Template.Element | Reactor.Template.Input | Reactor.Template.Result | Reactor.Template.Value		The value to match against.
description	String.t		An optional description for the step.
allow_async?	boolean	true	Whether the emitted steps should be allowed to run asynchronously.

reactor.switch.matches?

matches? predicate

A group of steps to run when the predicate matches.

Arguments

Name	Type	Default	Docs
predicate	(any -> any) | mfa		A one-arity function which is used to match the switch input. If the switch returns a truthy value, then the nested steps will be run.

Options

Name	Type	Default	Docs
allow_async?	boolean	true	Whether the emitted steps should be allowed to run asynchronously.
return	atom		Specify which step result to return upon completion.

Introspection

Target: Reactor.Dsl.Switch.Match

reactor.switch.default

If none of the matches? branches match the input, then the default steps will be run if provided.

Options

Name	Type	Default	Docs
return	atom		Specify which step result to return upon completion.

Introspection

Target: Reactor.Dsl.Switch.Default

Introspection

Target: Reactor.Dsl.Switch