Built-in get-type fails on a simple data construction

[ngeiswei]

What is the problem?

The built-in get-type does not work on a simple user defined type.

How to reproduce your problem?

Run the following program with MeTTaLog

(: Shape Type)
(: Box Shape)
(: Attribute Type)
(: MkShapeAttribute (-> Shape Attribute))
!(get-type (MkShapeAttribute Box))

What do you get?

[error [error [existence_error procedure [ / non_arg_violation_each 3 ]] [context [ / args_conform 4 ] $260]] [file /home/nilg/Work/SingularityNET/ai-dsl/experimental/ai-service-composition/english-to-chinese-song/bug.metta] (get-type (MkShapeAttribute Box))][

What would you normally expect?

[Attribute]

What else do you have to say?

The get-type calls on terms individually works, that is

!(get-type Shape)
!(get-type Box)
!(get-type Attribute)
!(get-type MkShapeAttribute)

properly outputs

[Type]
[Shape]
[Type]
[(-> Shape Attribute)]

It only fails when get-type is called on (MkShapeAttribute Box).