Syntax

https://en.wikipedia.org/wiki/Syntax_(programming_languages) https://en.wikipedia.org/wiki/Syntax_(logic)

The syntax of a programming language is the set of rules that defines the combinations of symbols that are considered to be expressions (correctly structured statements) in that language.

This applies equally to programming languages, where the document represents the source code, and to markup languages, where the document represents data.

In a programming language, an expressions is a correctly structured statement (in that language).

The syntax of a language defines its surface form.

Text-based programming languages are based on sequences of characters, while visual programming languages are based on the spatial layout and connections between symbols.

Documents that are syntactically invalid are said to have a syntax error.

Syntax refers to the form of the code, and is contrasted with semantics, the meaning.

During the processing of a programming language's document (source code), semantic processing generally comes after syntactic processing; however, in some cases, semantic processing is necessary for complete syntactic analysis.

In compilers, the syntactic analysis is traditionally located in a compiler's frontend, while the semantic analysis comprises a compiler's backend.

Computer language syntax is generally distinguished into 3 levels:

1. Words : the lexical level, determining how characters form tokens

2. Phrases: the grammar level, determining how tokens form phrases

3. Context: determines what objects or var names refer to

Distinguishing in this way yields modularity, allowing each level to be described and processed separately and often independently.

First, a lexer turns a linear sequence of characters into a linear sequence of tokens; this is known as lexical analysis (lexing).

Second, a parser turns a linear sequence of tokens into a hierarchical syntax tree; this is known as parsing (in a narrow sense).

Third, the contextual analysis resolves names and checks types.

This modularity is sometimes possible, but in many real-world languages an earlier step depends on a later step; for example, the lexer hack in C is because tokenization depends on context. Even in these cases, syntactical analysis is often seen as approximating this ideal model.

http://rigaux.org/language-study/syntax-across-languages/ http://rigaux.org/language-study/syntax-across-languages.html https://en.wikipedia.org/wiki/Category:Programming_language_syntax https://en.wikipedia.org/wiki/Formal_semantics_(natural_language) https://en.wikipedia.org/wiki/Computational_semantics https://en.wikipedia.org/wiki/Syntax_(programming_languages) https://en.wikipedia.org/wiki/Semantics_(computer_science) https://en.wikipedia.org/wiki/Semantics https://en.wikipedia.org/wiki/Denotational_semantics