Trait for pulling out some subset of an HList, using type inference.
This trait is part of the implementation of the inherent method
HCons::sculpt. Please see that method for more information.
You only need to import this trait when working with generic
HLists of unknown type. If you have an HList of known type,
list.sculpt() should “just work” even without the trait.
Required Associated Types§
Consumes the current HList and returns an HList with the requested shape.
Please see the inherent method for more information.
The only difference between that inherent method and this trait method is the location of the type parameters. (here, they are on the trait rather than the method)
Implementation for when the target is an empty HList (HNil)
Index type is HNil because we don’t need an index for finding HNil
Implementation for when we have a non-empty HCons target
Indices is HCons<IndexHead, IndexTail> here because the compiler is being asked to figure out the Index for Plucking the first item of type THead out of Self and the rest (IndexTail) is for the Plucker’s remainder induce.