Notation¶

This documentation uses Extended Backus-Naur Form (EBNF) to represent the Nite language syntax. EBNF can be hard to read at first, so we recommend giving this page at least a glance before reading the rest of the specification.

Grammar rules¶

A grammar rule has the form name = definition ;, where name is the name of the rule and definition is the grammar expression the rule matches.

identifier = identifier_start { identifier_continue } ;

The right-hand side is built from the following constructs:

Terminals are written in double quotes (e.g. "+") or in rare cases in single quotes (e.g. '"'), and match themselves literally.
Nonterminals are written in plain words (e.g. identifier) and match whatever the named rule defines.
Concatenation is an expression followed by another expression; both must match in order:
```
full_name = name , surname ;
```
Alternation is an expression followed by | followed by another expression; either may match:
```
integer_literal = decimal_literal | hex_literal | binary_literal ;
```

Optional is an expression wrapped in square brackets; it may match or be skipped:

numeric_literal = ( float_literal | integer_literal ) , [ numeric_suffix ] ;

Repetition is an expression wrapped in curly braces; it matches the expression zero or more times:
```
identifier_or_keyword = identifier_start { identifier_continue } ;
```

A group is an expression wrapped in parentheses, used to make precedence explicit:

float_literal  = decimal_literal , "." , decimal_literal
               | decimal_literal , [ "." , decimal_literal ] , float_exponent ;

Special sequences are wrapped in question marks and describe a match in words rather than symbols:

escaped_identifier_character
    = ? any Unicode scalar value except LF, CR, "\", and "`" ? ;

Reserved notation¶

A few characters are used by the notation itself (", |, [, ], {, }, (, ), ,, ?, =, ;). When a grammar needs to match one of these characters literally, it is written inside double quotes, e.g. ",".