Takashi Kato <ktakashi19@gmail.com> schrieb am Di., 28. Juni 2016 um 21:41 Uhr:

Hi,

Maybe I'm missing/misunderstanding the purpose of this SRFI, but what's the
point to have this? I don't see the reason why not SRFI-9/R6RS/R7RS records
as minimal disjoint type. Maybe not R6RS record since it has introspection.
(Though, you just need to specify opaque #f.)

Maybe one should say that this SRFI is a minimal extension to R7RS-small that provides *unique* and *subtypeable* types.

While they provide unique types, neither SRFI-9 nor R7RS-small records provide subtypes.

More sophisticated record systems like SRFI 131 or SRFI 136 provide subtypes. When the underlying implementations differ, however, it may not be possible to intertwine, say, SRFI 131, SRFI 136, and (rnrs records) in inheritance chains of subtypes.

If all implementations of record-type systems agree on using SRFI 137 for creating and subtyping types, they will at least be compatible in this regard.

Marc