Syntax desugaring

A large amount Clay syntax, including almost every operator, is actually simplified into plain function calls (or sequences of function calls) by the Clay compiler. This page aims to document all of these transformations.

In the following tables, a, b, c represent arbitrary single-value subexpressions. ...a, ...b, ...c represent zero or more arbitrary subexpressions yielding zero or more values. foo, bar, bas represent literal identifiers. a;, b;, c; represent an arbitrary statement (including an arbitrary { ... } block). 0, 1, 2 represent literal integers. In the "equivalent" column, _x, _y, _z represent nonaccessible temporary variable names.

All referenced function names are looked up in the prelude module unless otherwise indicated. Note that if, for example, you create a new function named add in a different module, that new function will not affect the behavior of the + operator. When overloading operators, you must use the overload keyword to modify the existing operator functions in their original modules.

Operator expressions

Operator expression	Equivalent function expression	Notes
+a	plus(a)
-a	minus(a)
&a	__primitives__.addressOf(a)	(1)
*a	(see Variant Dispatch)	(1)
a[...b]	index(a, ...b)
a(...b)	call(a, ...b)	(2)
a.foo	fieldRef(a, #foo)
a.0	staticIndex(a, static 0)
a^	dereference(a)
a * b	multiply(a, b)
a / b	divide(a, b)
a % b	remainder(a, b)
a + b	add(a, b)
a - b	subtract(a, b)
a < b	lesser?(a, b)
a <= b	lesserEquals?(a, b)
a > b	greater?(a, b)
a >= b	greaterEquals?(a, b)
a == b	equals?(a, b)
a != b	notEquals?(a, b)
new a	allocateShared(a)
if (a) b else c	ifExpression(a, b, c)	(3)
[...a]	arrayLiteral(...a)
()	tupleLiteral()
(a, ...b)	tupleLiteral(a, ...b)

Notes:

1. Not overloadable.
2. In the absence of a call overload for a static callable, the callable is invoked directly.
3. ifExpression only affects the expression form of if. if statements do not desugar into a function form.

Assignment operators

Assignment in Clay is not an expression; however, the assignment operators still desugar into function calls:

Assignment statement	Equivalent function statement	Notes
a = b;	assign(a, b);	(1)
a <-- b;	(see Initialization)
a *= b;	multiplyAssign(a, b);
a /= b;	divideAssign(a, b);
a %= b;	remainderAssign(a, b);
a += b;	addAssign(a, b);
a -= b;	subtractAssign(a, b);

Notes:

1. var a = b; and ref a = b; for rvalue b both behave like <-- instead of calling assign. See Initialization. ref a = b; for lvalue b and alias a = b; bind a to b respectively as a greedy or lazy alias; there are no function equivalents to those operations.

Control Flow

Control flow statement	Equivalent code
for (a in b) c;	{ ref _x = b; var _y = iterator(_x); while (hasNext?(_y)) { ref a = next(_y); c; } }
static for (a in ...b) c;	{ alias a = <first element of b>; c; } { alias a = <second element of b>; c; } /* ... */

Initialization

The initializing assignment operator a <-- b; initializes the values on the left side as if they are uninitialized memory. If the right side is a function expression (or an operator expression that desugars to a function expression), the top-level function is called, and it writes its return values directly into the values on the left-hand side. If the right-hand side is a simple variable name, or a call to a function that returns by reference, then the copy constructor for the type of the right-hand variable is i

Conditions	ExpressionFunction call
`f` is a function or operator that returns by value	a <-- f(...b);	f(...b)
`b` is a standalone variable, or an expression that returns by `ref` `a` is not a `forward` argument, or is a `forward`ed lvalue	a <-- b;	copy(b)
`b` is a standalone variable, or an expression that returns by `ref` `a` is a `forward`ed rvalue	a <-- b;	move(b)

Variant Dispatch