> There are important security and performance implications to opening a
> URI in place of a file. I've found generic URI opening useful mainly in
> simple scripts. If any `open` call in a complex application can turn
> into a `open-uri`, a security audit is difficult.

This could probably be mitigated by having a (path-remote? <path>)
predicate. Then open-file procedures and the like could ensure a
non-remote path.

Another point of concern is that many programs want to present a simple
interface to the outside world. APIs in the programming language that
accept fancy syntax (such as file: URIs in place of filenames) make this
difficult to ensure: e.g. a program reading a filename from a metadata
file will now be able to read URIs. Some other program reading the same
metadata file may not work with those URIs, supporting only traditional
filenames.

A similar problem is things like the ISO/POSIX C string->number
functions being lenient with leading zeros, whitespace and radix
prefixes. It's difficult to "just parse some digits" with C. Extensible
config parsing / logging frameworks now present similar interoperability
worries: e.g. CosmicConfig and Dhall are difficult to replicate in
another language.