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Unconstrained.mdx

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Container which holds an unconstrained value. This can be used to pass values between the out-of-circuit blocks in provable code.

Invariants:

  • An Unconstrained's value can only be accessed in auxiliary contexts.
  • An Unconstrained can be empty when compiling, but never empty when running as the prover. (there is no way to create an empty Unconstrained in the prover)

Example

let x = Unconstrained.from(0n);

class MyContract extends SmartContract {
  `@method` myMethod(x: Unconstrained<bigint>) {

    Provable.witness(Field, () => {
      // we can access and modify `x` here
      let newValue = x.get() + otherField.toBigInt();
      x.set(newValue);

      // ...
    });

    // throws an error!
    x.get();
  }

Type parameters

• T

Properties

provable

static provable: UnconstrainedProvable<any> & {
  "empty": () => Unconstrained<any>;
  "toInput": (x: Unconstrained<any>) => {
     "fields": Field[];
     "packed": [Field, number][];
    };
};

Type declaration

empty()
empty: () => Unconstrained<any>;
Returns

Unconstrained<any>

toInput()
toInput: (x: Unconstrained<any>) => {
  "fields": Field[];
  "packed": [Field, number][];
};
Parameters

• x: Unconstrained<any>

Returns
{
  "fields": Field[];
  "packed": [Field, number][];
}
fields?
optional fields: Field[];
packed?
optional packed: [Field, number][];

Source

lib/provable/types/unconstrained.ts:111

Methods

get()

get(): T

Read an unconstrained value.

Note: Can only be called outside provable code.

Returns

T

Source

lib/provable/types/unconstrained.ts:53

set()

set(value: T): void

Modify the unconstrained value.

Parameters

• value: T

Returns

void

Source

lib/provable/types/unconstrained.ts:67

setTo()

setTo(value: Unconstrained<T>): void

Set the unconstrained value to the same as another Unconstrained.

Parameters

• value: Unconstrained<T>

Returns

void

Source

lib/provable/types/unconstrained.ts:74

updateAsProver()

updateAsProver(compute: (value: T) => T): void

Update an Unconstrained by a witness computation.

Parameters

• compute

Returns

void

Source

lib/provable/types/unconstrained.ts:104

from()

static from<T>(value: T | Unconstrained<T>): Unconstrained<T>

Create an Unconstrained with the given value.

Note: If T contains provable types, Unconstrained.from is an anti-pattern, because it stores witnesses in a space that's intended to be used outside the proof. Something like the following should be used instead:

let xWrapped = Unconstrained.witness(() => Provable.toConstant(type, x));

Type parameters

• T

Parameters

• value: T | Unconstrained<T>

Returns

Unconstrained<T>

Source

lib/provable/types/unconstrained.ts:89

withEmpty()

static withEmpty<T>(empty: T): Provable<Unconstrained<T>, T> & {
  "empty": () => Unconstrained<T>;
  "toInput": (x: Unconstrained<T>) => {
     "fields": Field[];
     "packed": [Field, number][];
    };
}

Type parameters

• T

Parameters

• empty: T

Returns

Provable<Unconstrained<T>, T> & { "empty": () => Unconstrained<T>; "toInput": (x: Unconstrained<T>) => { "fields": Field[]; "packed": [Field, number][]; }; }

Source

lib/provable/types/unconstrained.ts:131

witness()

static witness<T>(compute: () => T): Unconstrained<T>

Create an Unconstrained from a witness computation.

Type parameters

• T

Parameters

• compute

Returns

Unconstrained<T>

Source

lib/provable/types/unconstrained.ts:97