type.unit_as_number: You declared a type named for a unit, such as Grams, Pence or Percent, on a plain number

You declared a type named for a unit, such as Grams, Pence or Percent, on a plain number.

Area 2, Values and types; declinable; the next step is usually the agent's.

Why Jadpo refuses it

A type built on Int or Decimal holds a number and nothing else, so its name is the only place the unit is written. A value in kilograms passes for one in grams, a price in pounds for one in pence, and the number adds to any other. The standard types keep the unit with the number: a Mass converts between units exactly and shows itself in the one you ask for, and a Money knows its currency.

Jadpo goes by the type's whole name, so it can be wrong: a name can be a unit by chance. That is a judgement call, so you can decline it with a reason, which review reads.

What it looks like

main.jadpo:

example

/// What a parcel weighs.type Grams = Int {    min: 1    max: 30000}

jadpo checkcheck failed: 1 error, 1 file

error Grams holds a Mass as a plain number

--> main.jadpo:2:6

  |2 | type Grams = Int {  |      ^^^^^ named for a unit

reason: Grams is named for a unit of Mass but is a plain Int, so nothing keeps the unit with the number: a value in another unit passes for one in this one, and it adds to any other number. A Mass carries what the number means, and converts and shows itself by its own rules.
next: Build it on Mass, named for what it holds rather than its unit, or write decline type.unit_as_number: "<why>" above it if this is deliberate (agent)
rule: type.unit_as_number
help: https://jadpo.dev/docs/errors/type.unit_as_number

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

A currency's minor unit is Money held as a whole number, so a price in pence is refused too.

main.jadpo:

example

/// What a loaf costs.type Pence = Int {    min: 0}

jadpo checkcheck failed: 1 error, 1 file

error Pence holds a Money as a plain number

--> main.jadpo:2:6

  |2 | type Pence = Int {  |      ^^^^^ named for a unit

reason: Pence is named for a unit of Money but is a plain Int, so nothing keeps the unit with the number: a value in another unit passes for one in this one, and it adds to any other number. A Money carries what the number means, and converts and shows itself by its own rules.
next: Build it on Money, named for what it holds rather than its unit, or write decline type.unit_as_number: "<why>" above it if this is deliberate (agent)
rule: type.unit_as_number
help: https://jadpo.dev/docs/errors/type.unit_as_number

How to fix it

The question is whether the type holds what its name says.

If it holds that unit's kind of value, build it on the standard type and name it for what it holds. main.jadpo becomes:

example

/// What a parcel weighs.type ParcelWeight = Mass {    min: 1g    max: 30kg}

A value now names its unit when it is made, as 250g or units.of(grams, MassUnit.gram), and a bare number where a ParcelWeight is expected is type.unit_required. A price is the same with Money:

example

/// What a loaf costs.type LoafPrice = Money {    currency: Currency.gbp    min: 0}

A LoafPrice is made from pence with money.from_minor, and adding it to a price in another currency doesn't compile.

If the name is a unit by chance, keep the type, and write a decline line with the reason directly above the declaration:

example

/// Knots the scouts can tie.decline type.unit_as_number: "Knots the scouts can tie, not a speed"type Knots = Int {    min: 0}

jadpo approval lists every decline with its reason, so a reviewer sees why it isn't the standard type.

Why Jadpo refuses it

What it looks like

How to fix it

Related