Packed
Packed<T>
is a "packed" representation of any type T
.
"Packed" means that field elements which take up fewer than 254 bits are packed together into as few field elements as possible.
For example, you can pack several Bools (1 bit) or UInt32s (32 bits) into a single field element.
Using a packed representation can make sense in provable code where the number of constraints depends on the number of field elements per value.
For example, Provable.if(bool, x, y)
takes O(n) constraints, where n is the number of field
elements in x and y.
Usage:
// define a packed type from a type
let PackedType = Packed.create(MyType);
// pack a value
let packed = PackedType.pack(value);
// ... operations on packed values, more efficient than on plain values ...
// unpack a value
let value = packed.unpack();
Warning: Packing only makes sense where packing actually reduces the number of field elements. For example, it doesn't make sense to pack a single Bool, because it will be 1 field element before and after packing. On the other hand, it does makes sense to pack a type that holds 10 or 20 Bools.
Type parameters
• T
Constructors
new Packed()
new Packed<T>(packed: Field[], value: Unconstrained<T>): Packed<T>
Parameters
• packed: Field
[]
• value: Unconstrained
\<T
>
Returns
Packed
\<T
>
Source
Properties
packed
packed: Field[];
Source
value
value: Unconstrained<T>;
Source
_innerProvable
static _innerProvable: undefined | ProvableExtended<any>;
Source
_provable
static _provable: undefined | ProvableHashable<Packed<any>>;
Source
Accessors
Constructor
get Constructor(): typeof Packed
Returns
typeof Packed
Source
innerProvable
get static innerProvable(): ProvableExtended<any>
Returns
ProvableExtended
\<any
>
Source
Methods
toFields()
toFields(): Field[]
Returns
Field
[]
Source
unpack()
unpack(): T
Unpack a value.
Returns
T
Source
create()
static create<T>(type: ProvableExtended<T>): typeof Packed & {
"provable": ProvableHashable<Packed<T>>;
}
Create a packed representation of type
. You can then use PackedType.pack(x)
to pack a value.
Type parameters
• T
Parameters
• type: ProvableExtended
\<T
>
Returns
typeof Packed
& {
"provable"
: ProvableHashable
\<Packed
\<T
>>;
}
Source
pack()
static pack<T>(x: T): Packed<T>
Pack a value.
Type parameters
• T
Parameters
• x: T
Returns
Packed
\<T
>