Chicken kind of felt like a dying ecosystem when I tried it, and it's also not very fast. The standard library itself is kind of limited, so if I couldn't find an egg for something I wanted to do, I felt very stuck.
Chez is good because it's supported by Akku, but I'm not sure if it will ever support R7RS. It does have a really nice FFI though, and the docs are very good.
R5RS is too small for real work unless you add tons of SRFIs, so they created R6RS for people who want to get stuff done. But the the R5RS people got ticked off because "its too big".
R7RS was supposed to be a compromise with a tiny R7RS-small, but later adding most of the R6RS features with R7RS-large. It's now been a decade and R7RS-large seems to be completely dead.
To put it in perspective, that is the amount of years that have taken C++ to adopt modules and concepts (still ongoing), Java to research and slowly start deploying Valhala, .NET to start having something better than NGEN / .NET Native across all workloads and beyond Windows, migrate an ecosystem to Python 3,....
We're talking the 2008 timeframe. When George Bush reigns and the biggest films are The Dark Knight and Iron Man. Halo 3, CoD4, and Crysis are new. Our latest generation of devs are just toddlers.
Stackoverflow is created.
The world is running on Windows Vista (XP actually, but that's another story).
Github is created.
Facebook pulls ahead of MySpace in user count for the first time.
Blu-ray finally beats HD-DVD.
People think the Large Hadron Collider will end the world when it turns on.
Randy Pausch's book "The Last Lecture" becomes a New York Times best seller.
First Android phone and iPhone 3g release this year with ARM11 CPUs. The App Store is brand new.
JS is still slow and Chrome releases to change that.
Amazon buys Audible.
Rust essentially doesn't exist.
AirBnb is founded.
Bitcoin doesn't exist yet (though the paper drops this year).
Memristor is finally proven to be possible.
The 46th Mersenne Prime is found.
USB-3 spec drops for companies to start working on.
Core i7, and Atom on 45nm are the latest CPUs (AMD also launched Phenom on 65nm). GTX280 and HD4870x2 are the fastest GPUs around and people are discussing how overpriced top-end GPUs are at $450-550 and complaining that these GPUs use 200-250w of power.
Tesla Roadster releases for about $100,000 and Musk launches the first car (promised to the actual founder) into space out of spite.
We aren't talking about the implementations, we're simply discussing the spec. Can you name another language spec that took over 15 years from conception to completion?
Even Common Lisp which languished for a terribly long time due to infighting didn't take that long despite being a much more comprehensive and difficult spec.
If you read carefully my original comment, you would have understood specs were part of the description.
Just as an example, C++ concepts were originally presented in 2005 [0], dropped in 2009 [1], redesigned as Concepts Lite in 2013 [2], graduated to technical specification in 2015 [3], added to C++20 roadmap in 2020 [4].
Making it 15 years to fully work out a language feature and related library functions, and even what came out 15 years is a subset of the original proposal, not going to bother with specification refinements after C++20.
Everything goes faster if it were us doing it, right?
Chez is good because it's supported by Akku, but I'm not sure if it will ever support R7RS. It does have a really nice FFI though, and the docs are very good.