Minilib.Monad.State
Defined in minilib-monad@0.5.1
State Monad which maintains a mutable state.
Values
namespace Minilib.Monad.State
eval_state
Type: s -> Minilib.Monad.State::State s a -> a
Runs a State monad with the supplied initial state and return the final value, discarding the final state.
eval_state_t
Type: [m : Std::Monad] s -> Minilib.Monad.State::StateT s m a -> m a
Runs a StateT monad with the supplied initial state and return the final value, discarding the final state.
exec_state
Type: s -> Minilib.Monad.State::State s a -> s
Runs a State monad with the supplied initial state and return the final state, discarding the final value.
exec_state_t
Type: [m : Std::Monad] s -> Minilib.Monad.State::StateT s m a -> m s
Runs a StateT monad with the supplied initial state and return the final state, discarding the final value.
lens_state
Type: ((s -> Minilib.Functor.Pair::PairLT a Minilib.Monad.Identity::Identity s) -> t -> Minilib.Functor.Pair::PairLT a Minilib.Monad.Identity::Identity t) -> Minilib.Monad.State::State s a -> Minilib.Monad.State::State t a
lens_state_t
Type: [m : Std::Monad, m : Std::Functor] ((s -> Minilib.Functor.Pair::PairLT a m s) -> t -> Minilib.Functor.Pair::PairLT a m t) -> Minilib.Monad.State::StateT s m a -> Minilib.Monad.State::StateT t m a
Transforms a state monad with a lens action.
For example, if Foo has a field bar: Bar, then act_bar is a function of type
[f: Functor] (Bar -> f Bar) -> (Foo -> f Foo).
Using act_bar, a state monad of Bar can be transformed to a state monad of Foo.
change_bar: StateT Bar IO ();
change_bar = ...;
change_foo: StateT Foo IO ();
change_foo = change_bar.lens_state_t(Foo::act_bar);
Note that act_xxx can be composed, for example Foo::act_bar << Bar::act_baz << Baz::act_qux.
make_state_monad
Type: (s -> (s, a)) -> Minilib.Monad.State::State s a
Creates a State monad from a function.
make_state_t_monad
Type: [m : Std::Monad] (s -> m (s, a)) -> Minilib.Monad.State::StateT s m a
Creates a StateT monad from a function.
map_state_t
Type: [m : Std::Monad, n : Std::Monad] (m (s, a) -> n (s, b)) -> Minilib.Monad.State::StateT s m a -> Minilib.Monad.State::StateT s n b
Maps both the return value and final state.
mod_state
Type: [sm : Minilib.Monad.State::MonadState] (Minilib.Monad.State::MonadStateIF::StateType sm -> Minilib.Monad.State::MonadStateIF::StateType sm) -> sm ()
A monad that modifies the current state with the specified function.
run_state
Type: s -> Minilib.Monad.State::State s a -> (s, a)
Runs a State monad with the supplied initial state.
run_state_t
Type: [m : Std::Monad] s -> Minilib.Monad.State::StateT s m a -> m (s, a)
Runs a StateT monad with the supplied initial state.
state
Type: (s -> (s, a)) -> Minilib.Monad.State::State s a
Synonym of make_state_monad.
state_t
Type: [m : Std::Monad] (s -> m (s, a)) -> Minilib.Monad.State::StateT s m a
Synonym of make_state_t_monad.
namespace Minilib.Monad.State::MonadStateIF
get_state
Type: [sm : Minilib.Monad.State::MonadStateIF] sm (Minilib.Monad.State::MonadStateIF::StateType sm)
A monad that returns the internal state as a value.
put_state
Type: [sm : Minilib.Monad.State::MonadStateIF] Minilib.Monad.State::MonadStateIF::StateType sm -> sm ()
A monad that puts the specified value to the internal state.
Types and aliases
namespace Minilib.Monad.State
State
Defined as: type State s = Minilib.Monad.State::StateT s Minilib.Monad.Identity::Identity
StateT
Defined as: type [m : *->*] StateT s m a = unbox struct { ...fields... }
State monad wraps a function from a initial state to a pair of a value and a final state.
field data
Type: s -> m (s, a)
Traits and aliases
namespace Minilib.Monad.State
trait [sm : *->*] sm : MonadStateIF
A trait for generic state monads that manages the internal state.
type StateType
Defined as: StateType sm
The type of the internal state.
method get_state
Type: sm (Minilib.Monad.State::MonadStateIF::StateType sm)
A monad that returns the internal state as a value.
method put_state
Type: Minilib.Monad.State::MonadStateIF::StateType sm -> sm ()
A monad that puts the specified value to the internal state.