type.unit_required: A plain number is given where a physical quantity, such as a length or a mass, needs its unit

A plain number is given where a physical quantity, such as a length or a mass, needs its unit.

Area 19, Standard library; not declinable; the next step is usually the agent's.

Why Jadpo refuses it

A quantity type, such as Length, holds an amount in a unit. A number alone could be any length: 90 could be centimetres, inches or metres. Mixing those up is the mistake the type exists to prevent, so a quantity is always made with its unit, and this error can never be declined.

A plain number still scales a quantity, by * and /.

What it looks like

main.jadpo:

example

type ShelfLength = Length {    max: 3metre}/// The shelf a kitchen gets unless the customer asks for another.function standard_shelf() -> ShelfLength {    return ShelfLength(90)}

jadpo checkcheck failed: 1 error, 1 file

error ShelfLength needs a unit, and 90 is a bare number

--> main.jadpo:7:24

  |7 |     return ShelfLength(90)  |                        ^^ no unit

reason: A Length is always made with its unit, so a number alone could be any length: a number without its unit is the mistake the type exists to prevent.
next: Write its unit after the number, such as 90metre, or make it with units.of(90, LengthUnit.metre) in any of LengthUnit's units (agent)
rule: type.unit_required
help: https://jadpo.dev/docs/errors/type.unit_required

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

Two quantities of different kinds, such as a mass and a length, can't be added either. That is a different error, type.arithmetic_operand, which names the two kinds.

main.jadpo:

example

type ShelfLength = Length {}type ShelfLoad = Mass {}/// What a shelf is rated for, with its length added by mistake.function rated(shelf_span: ShelfLength, load: ShelfLoad) -> ShelfLoad {    return ShelfLoad(load + shelf_span)}

jadpo checkcheck failed: 1 error, 1 file

error ShelfLoad and ShelfLength can't be added: a Mass and a Length are different kinds

--> main.jadpo:7:22

  |7 |     return ShelfLoad(load + shelf_span)  |                      ^^^^^^^^^^^^^^^^^ different kinds

reason: + works within one kind of quantity, in any of its units; a Mass and a Length are different kinds, so the sum means nothing.
next: Use values of one kind, or a product or quotient the table defines (agent)
rule: type.arithmetic_operand
help: https://jadpo.dev/docs/errors/type.arithmetic_operand

How to fix it

If the number is written in the code, write its unit after it:

example

    return ShelfLength(90cm)

The standard shelf is now 90 centimetres, and anyone reading the code sees the unit.

To make a quantity from a number and a unit your code holds, use units.of, such as units.of(90, LengthUnit.centimetre). It takes an Int or a Decimal and any unit of the kind.

Why Jadpo refuses it

What it looks like

How to fix it

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