Syntax and call rules

Goblin uses braces for blocks and does not use semicolons. A newline ends a statement, so each statement sits on its own line. Comments begin with # and continue to the end of the line.

Literals and collection syntax

Integer literals such as 42 and float literals such as 3.14 are decimal only. Strings use double quotes. They support \n, \t, \r, \", and \\. Any other escape sequence is a syntax error.

var names = ["Ada", "Linus"]
var user = {"name": "Ada", "active": true}

List, dictionary, call, parameter, and field lists do not accept a trailing comma. Dictionary keys and values are expressions, but keys should be stable values such as strings, integers, or booleans.

Statements and line breaks

Any expression can stand alone as a statement, but only a call, index, or member access may do so in a program: user.save(), "a,b".split(","), and func() { ... }() are valid statements, while a + b or a lone - 2 is rejected with expression value is not used, since a value that is computed and dropped is almost always a mistake. The REPL is the exception: there a bare expression such as 1 + 2 is evaluated and displayed.

Because a newline ends a statement, a line can only continue the previous one in places where the expression is visibly unfinished: after a binary operator, a comma, a dictionary colon, or inside an open (, [, or { of a literal. Ending a line with a complete expression and starting the next with an operator does not continue it. var a = 10 followed by a line - 2 is two statements, and the second is the unused-value error above rather than a silent 10 - 2.

var total = price * quantity +
    shipping
var discounted = (
    total - coupon
)
var files = {
    "a.txt": "first",
    "b.txt": "second"
}
print(files["a.txt"],
      files["b.txt"])

The same rule means else must follow the closing brace of its if on the same line, and two statements cannot share a line.

Names

Identifiers may not be Go keywords: names such as map, range, select, struct, go, or defer are reserved and rejected at check time, because compiled programs emit them as Go identifiers. A handful of names the generated code itself relies on — object, extension, builtin, fmt, _registry, Execute, and main — are reserved for the same reason, as is the whole family of identifiers shaped like _name_N (a leading underscore with a trailing _<digits> suffix, e.g. _err_0), which the transpiler uses for its own temporaries. Built-in function names like print or max are not reserved — see Scope and declarations for how user declarations shadow them.

Functions and calls

Function parameters are required unless they declare a default value with = or are captured by *args or **kwargs.

func report(name, limit = 10, *values, **options) {
    print(name, limit, values, options)
}

report("scores", 1, 2, visible=true)

Calls can use positional arguments, named arguments, * list expansion, and ** dictionary expansion. Positional arguments must come before named ones. Whether a particular built-in or method accepts names is API-specific: many small methods are positional-only. Use the documented parameter names or value.attributes() in the REPL to discover a value's available methods.