Constructor
new Step(get_maybe, updatedClone, construct)
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If standard logic for accessing data deeper in the conceptual structure is not adequate, an instance of this class may be passed as a step in a Lens, which will allow the Lens to have custom behavior.
Passing null for any of these functions will limit the functionality of
the lens: skipping either construct or updatedClone will prevent the lens
from constructing a missing container, skipping updatedClone will
additionally prevent the lens from modifying an existing container, and
skipping get_maybe will prevent retrieving or transforming values in
a subject.
Parameters:
| Name | Type | Description |
|---|---|---|
get_maybe |
Step~Get_Maybe | Returns a Maybe value for the slot within the container it is passed. |
updatedClone |
Step~UpdatedClone | Takes the current container and a Maybe of this step's slot value, returning a minimally modified clone of the container such that get_maybe will return the value_maybe passed to this function. |
construct |
Step~Construct | Instantiate an empty container of the type this step navigates. |
Type Definitions
Construct()
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Returns:
The empty container type corresponding to this step
Get_Maybe(container) → {Maybe.<*>}
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Gets the value of this slot within the passed container, returning {} if
the slot does not exist.
Parameters:
| Name | Type | Description |
|---|---|---|
container |
* |
Returns:
A Maybe monad value for the represented slot within container
- Type
- Maybe.<*>
UpdatedClone(container, value_maybe)
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Parameters:
| Name | Type | Description | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
container |
* | |||||||||
value_maybe |
Maybe.<*> |
Properties
|
Returns:
The minimally modified clone of container