/*
* opencog/atoms/scope/LambdaLink.h
*
* Copyright (C) 2015 Linas Vepstas
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License v3 as
* published by the Free Software Foundation and including the exceptions
* at http://opencog.org/wiki/Licenses
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program; if not, write to:
* Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef _OPENCOG_LAMBDA_LINK_H
#define _OPENCOG_LAMBDA_LINK_H
#include <opencog/atoms/scope/PrenexLink.h>
namespace opencog
{
/** \addtogroup grp_atomspace
* @{
*/
/// The LambdaLink is supposed to model the traditional concept
/// of a lambda from lambda calculus (or functional programming). It
/// is meant to behave like a combinator, and supports the standard
/// operations of beta-reduction and alpha-conversion (modulo that
/// alpha-equivalence is enforced when Atoms are inserted into the
/// AtomSpace). This is NOT "exactly" like a lambda-calculus-lambda;
/// there are subtle differences, because Atomese is a term algebra,
/// not a string algebra, and so assorted issues arise, that don't
/// occur in traditional settings.
///
/// The actual implementation of the alpha and beta reduction sits on
/// the PrenexLink, so this class is effectively a no-op, from the
/// C++ point of view. However...
///
/// However, we want to have this to minimize confusion in other,
/// distant parts of the code base. The issue is that there are many
/// other classes derived from PrenexLink, and they are NOT lambdas!
/// The most prominent example are the various PatternLinks; a simpler
/// example is the PutLink, which is a beta-redex and therefore cannot
/// ever be an actual lambda, although it derives from PrenexLink
/// to do it's beta-reduction. And so that's why we have a no-op C++
/// class, here.
///
class LambdaLink : public PrenexLink
{
public:
LambdaLink(const HandleSeq&&, Type=LAMBDA_LINK);
LambdaLink(const Handle& varcdecls, const Handle& body);
LambdaLink(const LambdaLink &) = delete;
LambdaLink& operator=(const LambdaLink &) = delete;
static Handle factory(const Handle&);
};
LINK_PTR_DECL(LambdaLink)
#define createLambdaLink CREATE_DECL(LambdaLink)
/** @}*/
}
#endif // _OPENCOG_LAMBDA_LINK_H