> To be fair, the Racket team has described its fork more as a “set of patches” that other­wise stays in sync with the main branch of Chez Scheme. Still, as time passes, the two will natu­rally tend to diverge further. Whether one calls it a “fork” or “set of patches”, the result is the same: some nonzero main­te­nance cost will persist, and likely grow.

Note that now Racket run on top of almost Chez Scheme. I think there are a few patches, but almost all the changes have been upstreamed.

The predictions from this post have almost entirely turned out to be wrong. Chez Scheme upstream decided to merge in Racket's changes entirely, and to make the lead developer of Racket (Matthew Flatt) a core Chez developer. These days Matthew is the most active Chez developer. Over the past few years, half of the serious Chez committers are people who come from Racket.