type.arithmetic_operand

A sum, difference or division mixes two different named types, or uses a value that isn't a number.

Area 3, Logic; not declinable; the next step is usually the agent's.

Why Jadpo refuses it

A named type such as Stock or Quantity is a unit. Multiplying a pack size by a number of packs means something, so * may mix types. Adding them doesn't: the sum of a stock level and a quantity is neither, and usually means the code reads the wrong value. So + and - need the same named type on both sides, or a literal, and / needs the same type too.

What it looks like

main.jadpo:

type Stock = Int {    min: 0}type Quantity = Int {    min: 1}function wrong_total(per_pack: Stock, packs: Quantity) -> Stock {    return Stock(per_pack + packs)}

   |10 |     return Stock(per_pack + packs)   |                  ^^^^^^^^^^^^^^^^ different types

(agent) at the end of the next: line means your coding agent can make the fix itself.

Dividing one named type by another is the same error. / divides two values of one type, and dropping the remainder is only one way to round:

main.jadpo:

type Stock = Int {    min: 0}type Boxes = Int {    min: 1}function per_box(items: Stock, boxes: Boxes) -> Stock {    return Stock(items / boxes)}

   |10 |     return Stock(items / boxes)   |                  ^^^^^^^^^^^^^ different types

A value that may be none is the error too, since none has no number. Its next: line says to match on the value and use it inside some(...), as in type.ordering_operand.

How to fix it

The question is what the code means to work out.

If the two values are the same unit, build one side as the other's type with its constructor, so both sides match:

    return Stock(per_pack + Stock(packs))

Stock(packs) checks the quantity against Stock's rules. A quantity is at least 1, so it is always a valid Stock, and building it can't fail.

If you meant the stock for that many packs, multiply, which may mix types:

    return Stock(per_pack * packs)

The result is the pack size times the number of packs.

If you are dividing two different types, use integer.divide, or decimal.divide for decimals, and name how to round:

    return Stock(integer.divide(items, boxes, rounding: Rounding.down))

Rounding.down drops the remainder, rounding toward zero. Rounding.half_even, half_up and up round the other ways (Numbers).

Related

• Expressions and operators
• Creating values
• Numbers