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Comment by mthom | Hacker News Reader

Some coming features of Scryer Prolog for those interested:

- Automatic detection and compilation of partial strings

- Streams, including sockets

- Garbage collection in anticipation of very fast yet logically pure I/O

- Improvements to the instruction dispatch loop (many opportunities for enhancement there, probably a good place to start for a beginning contributor)

In the past few months, we've added delimited continuations, tabling, partial strings, and Markus' CLP(B), CLP(ℤ) and format libraries. For a hobbyist project I'd say we're moving at a fairly quick pace!

Longer term, we're interested in:

- JIT compilation to native code (Cranelift seems a good candidate?)

- Low-level integration with Common Lisp environments

I'd love to have system-level contributors, although library contributions are always very welcome!

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I'm fairly new to programming in Prolog - how does Scryer Prolog compare to more common implementations like Swi Prolog?

Scryer is not yet as fast or feature-rich as SWI. SWI has been in business for about 30 years longer, so that shouldn't surprise anyone. Also, Scryer is committed to strict conformance to the ISO Prolog standard, which SWI has disregarded for a while now.

Thank you a lot Mark for participating in this discussion, and for all your work on Scryer Prolog during the last few years!

In the hope to attract further contributors to Scryer Prolog, especially with interest in Rust, I have now created a GitHub issue that collects a few self-contained features that could be interesting to look into for Rust programmers:

https://github.com/mthom/scryer-prolog/issues/319

I hope that's OK, and I invite everyone who is interested in these topics to contribute to this very innovative new Prolog system! Already in this early stage, it provides several important features that no other system currently has. Thank you again!

Yes, thank you for the Power of Prolog! Scryer was and is being written under its influence.

> very fast yet logically pure I/O

Sounds interesting, do you have a link or something else to share regarding your conception of logically pure I/O?

See https://github.com/mthom/scryer-prolog/issues/251

https://www.swi-prolog.org/pldoc/man?section=pio

https://github.com/SWI-Prolog/swipl-devel/blob/master/librar...

this (I assume) is the library(pio) mentioned in the github issue

From the interface (mostly yes, that, is apart from the impure extensions added later, and that chars are used and not codes) it is the same. But from the implementation behind it´s different. In particular from the space requirements. A text of n characters requires 3 * 8 * n bytes in SWI, but n + 2 * 8 bytes in Scryer. So there is a factor 24 in space requirements (on 64bit).

Also, there is now ample room for input that SWI once almost offered.

How usable is Scryer Prolog? Is it a single executable, or does it have a complex install?

Decently, I'd say. It is a single executable that you have to build yourself. If you want a recent build, there are a few extra steps, but they're nbd. There are build instructions in the README ("Installing Scryer Prolog") at:

http://github.com/mthom/scryer-prolog

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