LangSpecs

Language Specifications

Comment

Flatscript allows single-line comments whose content follows a # mark and ends at the line feed.

For example

# this comment possess a whole line
foo: bar + baz # this comment starts after a statement

No multi-line comment supported.

Structuring

Flatscript uses indentation to indicate blocks of code in scopes.

For example, a typical if-else branch is written as

if some_predicate
    console.log('consequence')
else
    console.log('alternative')

Those two console.log(...) are in two separated code blocks. The first one executes when some_predicate() returns something that if consider as true, while the second executes otherwise.

When a line contains an incomplete statement, the next line is considered as the succession.

For example

if foo < baz &&      # a
           fox < bar # b
    console.log(foo, bar  # c
              , baz)      # d

Line (a) and (b) are considered as one line because the predicate expression is not completed after a binary operator &&. Line (c) and (b) are also considered as one line because a closing parenthesis is needed to complete the function call syntax.

Identifiers and Reserved Words

Identifiers are used to represent a function or a class, or a name to a value or a constant. In Flatscript, an identifier

• starts with a underscore _ or an alphabet a-zA-Z
• followed by any number of underscores, alphabets, or numeric digits 0-9
• except for keywords, which are mentioned below

Please note that the dollar mark $ is not an identifier in Flatscript so that jQuery the identifier should be used instead.

The following are keywords

func ifnot if else return extern export typeof true false try catch throw
class this super ctor break continue for enum include

And the following are reserved words

from finally with yield while gen delete 

Keywords or reserved words are unable to use them as declare references, function names, class names or property names.

An identifier starts with two underscores and also ends up with two underscores is a macro that is not allowed to be a reference name, a function name or a class name, but could be used as a property name.

Javascript Runtime

Flatscript generates Javascript code, but is unable to make any modification to Javascript runtime. Therefore please note that

• the compiler is unable to check whether an object owns a property of a certain name
• the compiler is unable to determine the type of an object or whether an object is callable, or whether the number of arguments passed to a function call is the same as the number of its parameter
• the Javascript built-in function eval requires a string of valid Javascript, and still have a chance to fail because Flatscript compiler may change local reference names or even elimilate some of them for optimization

Topics

The following are the individual syntax topics that we suggest look over before using the language.

• expression
• name definition and lookup
• control flow
• function
• class
• export
• include

And topics about details of the compiler

• constant folding
• regular asynchonous