Solidity is an

object-oriented programming language Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...

for implementing smart contracts on various blockchain platforms, most notably,

Ethereum Ethereum is a decentralized, open-source blockchain with smart contract functionality. Ether (Abbreviation: ETH; sign: Ξ) is the native cryptocurrency of the platform. Among cryptocurrencies, ether is second only to bitcoin in market capita ...

. It was developed by Christian Reitwiessner, Alex Beregszaszi, and several former

core contributors. Programs in Solidity run on Ethereum Virtual Machine.

History

Solidity was proposed in August 2014 by

Gavin Wood Gavin James Wood (born 1980) is an English computer scientist, a founder of Ethereum and creator of Polkadot and Kusama. Early life Wood was born in Lancaster, England, United Kingdom. He attended the Lancaster Royal Grammar School. He gradua ...

; the language was later developed by the Ethereum project's Solidity team, led by Christian Reitwiessner. Solidity is the primary language on

as well as on other private blockchains, such as the enterprise-oriented

Hyperledger Hyperledger (or the Hyperledger Project) is an umbrella project of open source blockchains and related tools, started in December 2015 by the Linux Foundation, and has received contributions from IBM, Intel and SAP Ariba, to support the collabo ...

Fabric blockchain.

SWIFT Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...

deployed a proof of concept using Solidity running on Hyperledger Fabric.

Description

Solidity is a statically typed programming language designed for developing smart contracts that run on the Ethereum Virtual Machine (EVM). Solidity uses

ECMAScript ECMAScript (; ES) is a JavaScript standard intended to ensure the interoperability of web pages across different browsers. It is standardized by Ecma International in the documenECMA-262 ECMAScript is commonly used for client-side scripting o ...

-like syntax which makes it familiar for existing web developers; however unlike ECMAScript it has static typing and variadic return types. Solidity is different from other EVM-targeting languages such as Serpent and Mutan in some important ways. It supports complex member variables for contracts, including arbitrarily hierarchical mappings and structs. Solidity contracts support

inheritance Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Officia ...

, including

multiple inheritance Multiple inheritance is a feature of some object-oriented computer programming languages in which an object or class can inherit features from more than one parent object or parent class. It is distinct from single inheritance, where an object or ...

with

C3 linearization "In object-oriented systems with multiple inheritance, some mechanism must be used for resolving conflicts when inheriting different definitions of the same property from multiple superclasses." C3 superclass linearization is an algorithm used prim ...

. Solidity introduces an

application binary interface In computer software, an application binary interface (ABI) is an interface between two binary program modules. Often, one of these modules is a library or operating system facility, and the other is a program that is being run by a user. An ...

(ABI) that facilitates multiple

type-safe In computer science, type safety and type soundness are the extent to which a programming language discourages or prevents type errors. Type safety is sometimes alternatively considered to be a property of facilities of a computer language; that is ...

functions within a single contract (this was also later supported by Serpent). The Solidity proposal also includes "Natural Language Specification", a documentation system for specifying user-centric descriptions of the ramifications of method-calls. Example of a Solidity program: // SPDX-License-Identifier: GPL-3.0 pragma solidity ^0.8.4; contract Coin

Development platform availability

* JetBrains IntelliJ Plugin * Microsoft Visual Studio * Microsoft Visual Studio Code

Blockchain platforms

Solidity is available on: * Avalanche C-Chain *

Binance Smart Chain Binance is a cryptocurrency exchange which is the largest exchange in the world in terms of daily trading volume of cryptocurrencies. It was founded in 2017 and is registered in the Cayman Islands. Binance was founded by Changpeng Zhao, a deve ...

Counterparty A counterparty (sometimes contraparty) is a legal entity, unincorporated entity, or collection of entities to which an exposure of financial risk may exist. The word became widely used in the 1980s, particularly at the time of the Basel I deliberat ...

(which runs on Bitcoin) *

Ethereum Classic Ethereum Classic is an open source, blockchain-based distributed computing platform featuring smart contract (scripting) functionality. It supports a modified version of Nakamoto consensus via transaction-based state transitions executed on a p ...

Tron ''Tron'' (stylized as ''TRON'') is a 1982 American science fiction action- adventure film written and directed by Steven Lisberger from a story by Lisberger and Bonnie MacBird. The film stars Jeff Bridges as Kevin Flynn, a computer programmer ...

* Hedera Hashgraph

Criticism

Many security properties of smart contracts are inherently difficult to reason about directly, and the Turing-completeness of Solidity means that verification of arbitrary properties cannot be decidably automated. Current automated solutions for smart contract security analysis can miss critical violations, produce false positives, and fail to achieve sufficient code coverage on realistic contracts. Solidity has been blamed for the error-prone implementation of Ethereum smart contracts due to its counterintuitive nature, its lack of constructs to deal with blockchain domain-specific aspects, and its lack of centralized documentation of known vulnerabilities. In 2016, a

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...

researcher stated that Solidity was partially to blame for The DAO hack that took place that year. He stated: "this was actually not a flaw or exploit in the DAO contract itself: technically the Ethereum Virtual Machine (EVM) was operating as intended, but Solidity was introducing security flaws into contracts that were not only missed by the community, but missed by the designers of the language themselves."

References

{{Cryptocurrencies Domain-specific programming languages Statically typed programming languages Ethereum