Comparison of programming languages (syntax)This comparison of programming languages compares the features of language syntax (format) for over 50 computer programming languages. Programming language expressions can be broadly classified into four syntax structures: prefix notation Lisp (* (+ 2 3) (expt 4 5)) infix notation Fortran (2 + 3) * (4 ** 5) suffix, postfix, or Reverse Polish notation Forth 2 3 + 4 5 ** * math-like notation TUTOR (2 + 3)(45) $$ note implicit multiply operator When a programming languages has statements, they typically have conventions for: statement separators; statement terminators; and line continuation A statement separator demarcates the boundary between two separate statements.
At signThe at sign, , is an accounting and invoice abbreviation meaning "at a rate of" (e.g. 7 widgets @ £2 per widget = £14), now seen more widely in email addresses and social media platform handles. It is normally read aloud as "at" and is also commonly called the at symbol, commercial at, or address sign. The absence of a single English word for the symbol has prompted some writers to use the French arobase or Spanish and Portuguese arroba, or to coin new words such as ampersat and asperand, or the (visual) onomatopoeia strudel, but none of these have achieved wide use.
Off-side ruleA computer programming language is said to adhere to the off-side rule of syntax if blocks in that language are expressed by their indentation. The term was coined by Peter Landin, possibly as a pun on the offside rule in association football. This is contrasted with free-form languages, notably curly-bracket programming languages, where indentation has no computational meaning and indent style is only a matter of coding conventions and formatting. Off-side-rule languages are also described as having significant indentation.
String interpolationIn computer programming, string interpolation (or variable interpolation, variable substitution, or variable expansion) is the process of evaluating a string literal containing one or more placeholders, yielding a result in which the placeholders are replaced with their corresponding values. It is a form of simple template processing or, in formal terms, a form of quasi-quotation (or logic substitution interpretation). The placeholder may be a variable name, or in some languages an arbitrary expression, in either case evaluated in the current context.
Anonymous functionIn computer programming, an anonymous function (function literal, lambda abstraction, lambda function, lambda expression or block) is a function definition that is not bound to an identifier. Anonymous functions are often arguments being passed to higher-order functions or used for constructing the result of a higher-order function that needs to return a function. If the function is only used once, or a limited number of times, an anonymous function may be syntactically lighter than using a named function.
Object-oriented programmingObject-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 procedures (often known as methods). A common feature of objects is that procedures (or methods) are attached to them and can access and modify the object's data fields. In this brand of OOP, there is usually a special name such as or used to refer to the current object.
Reserved wordIn a computer language, a reserved word (also known as a reserved identifier) is a word that cannot be used as an identifier, such as the name of a variable, function, or label – it is "reserved from use". This is a syntactic definition, and a reserved word may have no user-defined meaning. A closely related and often conflated notion is a keyword, which is a word with special meaning in a particular context. This is a semantic definition. By contrast, names in a standard library but not built into a language are not considered reserved words or keywords.
String literalA string literal or anonymous string is a literal for a string value in the source code of a computer program. Modern programming languages commonly use a quoted sequence of characters, formally "bracketed delimiters", as in x = "foo", where "foo" is a string literal with value foo. Methods such as escape sequences can be used to avoid the problem of delimiter collision (issues with brackets) and allow the delimiters to be embedded in a string. There are many alternate notations for specifying string literals especially in complicated cases.
