Skip to main content

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(packed, value)​

new Packed<T>(packed: Field[], value: Unconstrained<T>): Packed<T>

Parameters​

• packed: Field[]

• value: Unconstrained\<T>

Returns​

Packed\<T>

Source​

lib/provable/packed.ts:77

Properties​

packed​

packed: Field[];

Source​

lib/provable/packed.ts:46

value​

value: Unconstrained<T>;

Source​

lib/provable/packed.ts:47

_innerProvable​

static _innerProvable: undefined | ProvableExtended<any>;

Source​

lib/provable/packed.ts:119

_provable​

static _provable: undefined | ProvableHashable<Packed<any>>;

Source​

lib/provable/packed.ts:118

Accessors​

Constructor​

get Constructor(): typeof Packed

Returns​

typeof Packed

Source​

lib/provable/packed.ts:121

innerProvable​

get static innerProvable(): ProvableExtended<any>

Returns​

ProvableExtended\<any>

Source​

lib/provable/packed.ts:125

Methods​

toFields()​

toFields(): Field[]

Returns​

Field[]

Source​

lib/provable/packed.ts:113

unpack()​

unpack(): T

Unpack a value.

Returns​

T

Source​

lib/provable/packed.ts:98

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​

lib/provable/packed.ts:52

pack()​

static pack<T>(x: T): Packed<T>

Pack a value.

Type parameters​

• T

Parameters​

• x: T

Returns​

Packed\<T>

Source​

lib/provable/packed.ts:85