PLT Scheme 4.0 released | Hacker News Reader

PLT Scheme 4.0 released

blog.plt-scheme.org

22 pointsstassats8 comments

I have no experience with lisp or scheme, but reading the new tutorial on their website was such a beautiful introduction to programming, and then I looked at the source code for the tutorial and was blown away at the level of simplicity and sophistication they have achieved.

So why have I never heard of PLT Scheme? Why isn't it popular?

I think it's probably the premiere Scheme implementation. Arc is built in it (you may have heard only of MzScheme, but that's in the PLT family). I happen to be using it for my startup.

As far as various Schemes go, I'd say it's very popular.

Stumbled upon this while checking out the blog:

http://www.youtube.com/watch?v=vgQO_kHl39g&fmt=18

Very impressive. The features in Dr. Scheme make for an excellent teaching environment, but look like they would work well for a working programmer, also.

What do you think about the set-car! thing? Why not just use Erlang instead?

Can you elaborate?

Maybe I misunderstood, but it seems to me that without set-car!, Scheme becomes more like Erlang in respect to "unchangeable variables" (don't remember the proper term right now).

I had recently evaluated Erlang but found some things very difficult to achieve. For a contrieved problem, how do you program an effective algorithm to calculate prime numbers in Erlang?

So I felt quite good about the destructive operators of Scheme. If they are now wanted anymore, I might reconsider using Erlang.

My understanding of the situation is that the PLT people had some optimizations they could do if lists were immutable, and they noticed that there were very few places in their code where they mutated lists. So they decided to just make lists immutable and see who complained. And it turns out few other people were actually mutating lists, so they kept the optimization.

PLT Scheme still has other mutable data structures that can be used instead of lists, though; I don't know if this is the case for Erlang.

Wow, they made the site much cleaner as well.

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