lean2/src/library/num.h

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/*
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#include "util/numerics/mpz.h"
#include "kernel/environment.h"
namespace lean {
/**
\brief Return true iff the environment \c env contains the following declarations
in the namespace 'num'
one : pos_num
bit0 : pos_num -> pos_num
bit1 : pos_num -> pos_num
zero : num
pos : pos_num -> num
*/
bool has_num_decls(environment const & env);
/**
\brief Return an expression that encodes the given numeral in binary using
the declarations one, bit0, bit1, zero, pos.
\see has_num_decls
\pre n >= 0
\post *to_num(from_num(n)) == n
*/
expr from_num(mpz const & n);
/**
\brief If the given expression encodes a numeral, then convert it back to mpz numeral.
\see from_num
*/
optional<mpz> to_num(expr const & e);
}