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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
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Subject: Re: "end of declaration"
Date: Thu, 11 Feb 2021 00:43:20 +0200
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On 2021-02-10 23:08, Shark8 wrote:
>> otherwise, operations for t_proba are redefined in the visible
>> (and  body) part so recursion will occur.
> What?
> No, "Type J is new K" gives you a completely new type.

Yes, but J inherits all primitive operations of K. And you can 
type-convert between J and K with no loss of information.

> To use a function that requires a K-value with a J-value you have to
> explicitly convert; given "Steve : J" and "-"(Right: K) return K, you
> would have to use -(K(Steve)) to call the unary-minus for K.
If the "-" function is a primitive operation of K, there is an identical 
inherited operation for J. If the "-" with a K-parameter is not 
primitive for K, it is not inherited by J, and a J-value j must be 
converted to a K-value before that "-" is called: - K(j).

You can override the inherited "-" with a new operation, specific to J. 
Within that operation, calling "-" on a J-value j would make it 
recursive. The K-operation can be called with - K(j) and that will not 
be a recursive call.