DA.Action.State

Daml 标准库模块 DA.Action.State 参考文档。

DA.Action.State

DA.动作.状态

模块快照

Stable. 状态：`active` 引入于：`3.4.9` 删除于：`-` 警告：`0` 弃用：`0` 已弃用自：`-`

数据类型

`data State s a`

A value of type `State s a` represents a computation that has access to a state variable
of type `s` and produces a value of type `a`.

>>> runState (modify (+1)) 0
((), 1)

>>> evalState (modify (+1)) 0
()

>>> execState (modify (+1)) 0
1

>>> runState (do x <- get; modify (+1); pure x) 0
(0, 1)

>>> runState (put 1) 0
((), 1)

>>> runState (modify (+1)) 0
((), 1)

Note that values of type `State s a` are not serializable.

构造函数：

State |领域|类型 |描述 | | :---- | :--- | :---------- | |运行状态| s -> (a, s) | s -> (a, s) | |

实例：

instance ActionState s (State s)
instance Action (State s)
instance Applicative (State s)
instance GetField runState (State s a) (s -> (a, s))
instance SetField runState (State s a) (s -> (a, s))
instance Functor (State s)

函数

`evalState`

evalState : State s a -> s -> a

runState 的特殊情况，不返回最终状态。

`execState`

execState : State s a -> s -> s

runState 的特殊情况，仅重新调整最终状态。

孤立类型类实例

instance Functor (State s)
instance Applicative (State s)
instance Action (State s)
instance ActionState s (State s)

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