Blockchain is a disruptive technology that has attracted the attention of the scientific community and companies, as proven by the exponential growth of publications on this topic in recent years. This growing interest is mainly due to the promise that the use of blockchain enables it to be verified, without including any trusted intermediaries, that the information received from the network is authentic and up-to-date. In this respect, blockchain is a distributed database that can be seen as a ledger that records all transactions that have ever been executed. In this context, smart contracts are pieces of software used to facilitate, verify, and enforce the negotiation of a transaction on a blockchain platform. These pieces of software are implemented by using programming languages, which are sometimes provided by the blockchain platforms themselves. This study aims to (1) identify and categorise the state-of-the-art related to smart contract languages, in terms of the existing languages and their main features, and (2) identify new research opportunities. The review has been conducted as a multivocal mapping study that follows the guidelines proposed by Garousi et al. for conducting multivocal literature reviews, as well as the guidelines proposed by Kitchenham and Charters for conducting mapping studies. As a result of the implementation of the review protocol, 4,119 papers were gathered, and 109 of them were selected for extraction. The contributions of this article are twofold: (1) 101 different smart contract languages have been identified and classified according to a variety of criteria; (2) a discussion on the findings and their implications for future research have been outlined. As a conclusion, it could be stated that a rigorous and replicable overview of the state-of-the-art of smart contract languages has been provided that can benefit not only researchers but also practitioners in the field, thanks to its multivocal nature.

中文翻译：

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智能合约语言

区块链是一种颠覆性技术，已引起科学界和公司的关注，近年来有关该主题的出版物呈指数增长就证明了这一点。这种日益增长的兴趣主要是由于承诺使用区块链可以在不包括任何可信中介的情况下验证从网络接收到的信息是真实的和最新的。在这方面，区块链是一个分布式数据库，可以看作是一个记录所有曾经执行过的交易的账本。在这种情况下，智能合约是用于在区块链平台上促进、验证和执行交易协商的软件。这些软件是通过使用编程语言实现的，有时由区块链平台本身提供。本研究旨在 (1) 根据现有语言及其主要特征对与智能合约语言相关的最新技术进行识别和分类，以及 (2) 确定新的研究机会。该审查是按照 Garousi 等人提出的指南进行的多声映射研究。进行多语言文献综述，以及 Kitchenham 和 Charters 提出的进行绘图研究的指南。作为审查方案实施的结果，收集了 4,119 篇论文，其中 109 篇被选中进行提取。本文的贡献有两个：（1）已经根据各种标准识别和分类了 101 种不同的智能合约语言；(2) 概述了对研究结果及其对未来研究的影响的讨论。作为结论，可以说，由于其多语言性质，已经提供了对最先进的智能合约语言的严格且可复制的概述，不仅可以使研究人员受益，而且可以使该领域的从业者受益。