Syntax

Meta: this page is the boring foundation. Focus on what would surprise someone coming from JS/Go/Python (semicolons-optional, newline-as-separator, # not //, no trailing commas in formatted output). Move grammar rules to reference/grammar.md.

File layout

a file is a sequence of forms separated by newlines or commas
whitespace is significant only as separators; indentation is conventional, not syntactic

Comments

# to end of line
placed on their own line or trailing; both are idiomatic
formatter keeps them attached to the following or preceding code

Meta: /// doc comments don't exist — docstrings are real triple-quoted strings attached to declarations (covered in Fields: pub and let and Functions).

a docstring is a triple-quoted string placed immediately before a declaration (module-level, field, function, or let)

Identifiers

lowercase: foo_bar, userName — values and methods
capitalized: User, String — types
single lowercase letters in type positions (a, b) — type variables
_ is a normal identifier character, not a special "ignore"/discard pattern

Reserved words

pub, let, type, interface, enum, union, scalar, new, implements
if, else, case, for, break, continue, return
try, catch, raise
import, directive, on
true, false, null
and, or
self

Separators and trailing commas

newlines and commas are interchangeable inside lists, arg lists, object literals
formatter strips trailing commas

Backticks and string-template lexer mode

backtick strings are templates with ${expr} interpolation
inside backticks, # is NOT special — it's a literal character, not a comment
the only escape recognized inside a template is \${, which emits a literal ${ (no other backslash escapes; \d+ stays \d+)
multi-line backtick fences (3, 4, 5+ backticks) for nested code blocks; the close fence must match the open fence length
see Literals