circuit.go

// Copyright 2020-2025 Consensys Software Inc.
// Licensed under the Apache License, Version 2.0. See the LICENSE file for details.

package frontend

// Circuit must be implemented by user-defined circuit. The best way to define a
// circuit is to define a type which contains all the witness elements as fields
// and declare `Define` method on the type.
//
// For example, the following is a minimal valid circuit:
//
//	type MyCircuit struct {
//	    X frontend.Variable `gnark:"-,public"`
//	    Y frontend.Variable `gnark:"-,secret"`
//	}
//
//	func (c *MyCircuit) Define(api frontend.API) error {
//	    api.AssertIsEqual(c.X, c.Y)
//		return nil
//	}
//
// See the documentation for [schema.TagOpt] for how to use tags to define the
// behaviour of the compiler and schema parser.
type Circuit interface {
	// Define declares the circuit's Constraints
	Define(api API) error
}