operand

SSA IR can be reasonably constructed from any of stack, accumulator, two-operand register or three operand register bytecode.

This contrasts them with three-operand or even one operand instructions sets, where adding two values can have several encodings.

If the type of the operand is a variable length array type, the operand is evaluated; otherwise, the operand is not evaluated and the result is an integer constant.

The size is determined from the type of the operand.

Or is it more like you pass the multiply function the first operand (2 in this case) and it returns a function multiply-by-2 which you pass the second operand?

Even some of the recent extensions to x86-64 are three operand versions of (some of) the vector instructions.

Two-address instructions suffice: simply have a register for the first operand that contains a value that is used later.

If you think three-operand instructions aren't common in both hardware and interpreter design, you are simply misinformed.

You need general purpose operand insns for only one or two fixed registers (eax, edx typically).

That map function looks a lot like it has 2 arguments, a function and an operand array (ie a list)??

AVX rolls up all the previous SSE versions, and provides 3-operand versions of those instructions.

Special purpose instructions that access fixed registers would be fine, but general purpose operand references cannot be sanely implemented in this way.

Magic concatenation: the "+" operator is understood by the compiler to be the concatenation operator if either operand is a String.

In the case of subtraction ("1" - 1), Number is called on any non-numeric operand.

Sure, free except that every dereference has to clear out those bits, unless the target architecture has a "pointer deref ignoring lower n bits" operator/operand.

Unsigned numbers in C++ are completely unsuitable for restricting the domain range because their "rank" (technical term) is higher than that of equally-sized signed types, which means that all operands are promoted to unsigned if one operand is unsigned.