There's also noticeably different idiomatic programming. An idiomatic Scheme programmer might do things like avoid mutations, leverage tail call optimization, use only hygienic macros syntax extension and maybe fancy tools for that e.
For CL, those things would be different, but I think also doable and more proven already. I do think I could get a team up to speed on Scheme faster than CL, because I can say "This week, use the core language, plus these packages, and then next week there's some non-obvious idiomatic stuff that I'd like to propose we learn, but I have to explain it, because it's not in any book I know of.
Scheme is more than powerful enough to implement all of these ideas, plus ideas more complex than you are used to using. It simply means that they we will have to find an implementation of the idea, or roll our own.
For example, I know of a couple of canonical implementations of object-oriented programming primitives for Scheme. Of course, as you'll see later in the semester, we can implement OOP concepts on our own in relatively little code. So, people write their own and share. That creates a portability problem. Unless a programmer implements a library using only standard Scheme, there is a risk that you won't be able to use the library on your system.
It may sound easy to use only standard Scheme, but in the heat of implementing a big package it is awfully tempting sometimes to use some of the non-standard features available in your environment.
Scheme is different than most other languages programmers use. It looks different, with all those parentheses and lambda s. It feels different, with its emphasis on functional programming and no side effects. Unfamiliarity can be a weakness, because it makes the language less immediately accessible to new programmers. It takes more effort to learn, because it changes the programmer's habits.
The use of function composition and higher-order procedures we'll talk about that soon! Unlike Java and Ada, there isn't much dead space or many dead characters. When a programmer is used to roomier code, Scheme code can intimidate them. The good news is that these weaknesses can be overcome by time and effort. The unfamiliar can become familar. And on the other side is a productivity and a sense of power that is hard to imagine when slogging away in Java, C, or Ada. The lambda calculus is in many ways the prototype for all programming languages.
Like the Turing machine, it is capable of implementing any computable function. Unlike the Turing machine, it focuses on the transformation rules that implement a function, rather than the underlying machine implementation.
Hence it lies closer to the level of software than the Turing machine. You can read a lot more about the lambda calculus at the Monash University site. You shouldn't be surprised later in the course when we use and interpret a subset of Scheme that is remarkably similar to Church's calculus.
Because Scheme is minimal, it leaves us a lot of freedom to talk about most every language feature, what they are useful for, how to implement them, and what trade-offs they impose on us. Because Scheme is minimal, it is small enough for us to master it well enough to implement language interpreters in it. Learn more. How is Racket different from Scheme? Ask Question. Asked 11 years, 3 months ago.
Active 4 years, 3 months ago. Viewed 60k times. Improve this question. Paul Roub Add a comment. Active Oldest Votes. With that said, the main points where it is not backwards compatible are: Racket has no set-cdr! In Racket, a lot of things are self-evaluating which would raise an error in R5RS, most importantly the empty list.
Racket is case sensitive, though R6RS is also case sensitive Racket treats There are probably more, but on most other parts racket is a superset of Scheme. Improve this answer. Will Ness Zorf Zorf 5, 1 1 gold badge 25 25 silver badges 24 24 bronze badges. In Racket is invalid, not self-evaluating. Eli, whoops, you're right, racket running in Swindle mode seems to consider self evaluating, I was confused with that one.
I never really got why was not self-evaluating in Scheme as it is in Common Lisp though. This answer should be updated. Racket's feature set far outweighs Scheme's now, with modules and language definitions, etc. But Racket still out-dos the R6RS feature set. Show 1 more comment. I think the rename was because they didn't want to be some dialect of Scheme with a bunch of nonstandard additions — they wanted to be a Scheme-based language with a bunch more stuff standard. Classifying PLT Scheme as "just" a dialect of Scheme is like classifying Ruby as a dialect of Mirah — it's not inaccurate, but it kind of downplays the language's strengths.
I think using a different name is a wise decision: using the same name for different languages that have a common origin is IMO confusing. I would change the name even if the language contained Scheme as a subset but contained so many additions that it would encourage a very different programming style.
Norman Gray Norman Gray Massimiliano Kraus 3, 5 5 gold badges 22 22 silver badges 44 44 bronze badges.
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