Grammar

Learning a programming language in the grammar-point of view helps you to achieve it faster.

This is No's grammar — the rules of the language and the guide of parser implementing. Completely knew it, you can learn any scripting language in the world easily.

We are presenting in pseudo code like regex.

Program

program := (decl | stmt)*

A program or a single file contains multiple declarations and statements.

Declarations

A declaration always starts with a keyword: use, class, func, or var.

decl := use_decl
      | class_decl
      | func_decl
      | var_decl

Declarations

Statements

stmt := block_stmt
      | break_stmt
      | continue_stmt
      | for_stmt
      | if_stmt
      | puts_stmt
      | return_stmt
      | switch_stmt
      | throw_stmt
      | try_stmt
      | while_stmt
      | (assign | increment | decrement | call)

The last group is also called "expression statement". In JavaScript, it allows any expression, make sure you do not cause a syntax conflict.

Here, we limit to only active-expressions: assign, increment, decrement and call. That makes the language be clear and no redundant things.

Statements

Expressions

expr := array
      | assign
      | binary
      | call
      | logical
      | map
      | increment
      | decrement
      | ternary
      | unary
      | primary

Expressions

Values (primary)

This is the smallest unit in the program.

primary := IDENTIFIER
         | NUMBER
         | STRING
         | LITERAL

IDENTIFIER

In our language, the keywords are not reserved words, they are just identifiders. So you can use them everywhere, except variable names.

This is the pattern of parsing is:

[a-zA-Z_$][a-ZA-Z0-9_$]*

An identifier is not a string, it present a "name".

abc
def_g
a_123

STRING

A string always inside single-quotes or double-quotes.

'this is string'
"this is string too"

We also supports slash-escape.

'Hi guys\n'

To write string in multi-line, just use two ` ` (grave accent).

`this is
a multi-line
string`

It looks like JavaScript, but we do not support string templating or string interpolation.

NUMBER

We supports 3 kinds of number: decimal, binary and hexadecimal.

123
3.14
100.99

0b11
0b100

0x10
0xabc
0xAf20

Be care while calling methods of a number. 123.str() is incorrect syntax, please group it: (123).str().

LITERAL

We have 3 keywords present literal values: null, true and false.

null
true
false