Re: question on variant record

[mheaney@ni.net (Matthew Heaney)]

In article <dewar.847999613@merv>, dewar@merv.cs.nyu.edu (Robert Dewar) wrote:

>Matthew Heany said
>
>"The technical term is "discriminant," not "tag field."  And technically, a
>"variant record" is a discriminant record only with a variant part (case
>statement).  You probably meant "discriminant record" in your subject line."
>
>variant record is a perfectly good term, see for example para 35 of the
>introduction to the RM:
>
>35   Record, task, and protected types may have special components called
>discriminants which parameterize the type.  Variant record structures that
>depend on the values of discriminants can be defined within a record type.
>
>
>variant_part is a perfectly good syntactic term, so the term variant
>record is a perfectly reasonable one, it  means a record with a variant
>part.
>
>The other term is discriminaTED record, which is a record type with
>discriminants. Note that all variant records have discriminants, but
>not all records with discriminants have variant parts, so variant record
>is a useful term.
>
>P.S. the term discriminant record is not used in the RM.

I stand corrected.  Thank you for clarifying this.

M.

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Matthew Heaney
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