es-discuss Digest, Vol 106, Issue 46

Brendan Eich brendan.eich at
Wed Dec 16 13:57:33 UTC 2015

A union is a kind of sum type -- either this or that. Order may matter for
reflective use-cases, indeed. That's a good point. Whether symbol values by
default are best wants a bit more debate too, I think.


On Wed, Dec 16, 2015 at 8:53 AM Coroutines <coroutines at> wrote:

> On Wed, Dec 16, 2015 at 5:44 AM, Brendan Eich <brendan.eich at>
> wrote:
> > `enum` has precedent -- C-like languages indeed use integers by default,
> but
> > see Rust for a generalized form:
> > -- for a category-theory "sum" type and IMHO handily beats `sym` or
> `sum`.
> I just mean that using `enum` to define symbols/identifiers sounds
> odd, as enum is short for 'enumerate' no?  We wouldn't be enumerating
> symbols as that suggests order behind the symbol
> identifiers/references, imo :>
> Rust's enum/sum value type sounds like a typed union..  the type flag
> is just hidden?
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