Even if possible, such redefinitions are not something that you should do without really understanding how the system will react to this. For example, if you redefine +, will any other code break? The answer to that in Racket’s case is “no” — but this is because you don’t really get to redefine +: instead, … Read more
Use Scheme. It is one of the simplest and easiest languages in existence, and you will spend very little time learning enough of it to understand SICP. Once you understand SICP, you will see how the concepts apply in any language.
current-milliseconds is a function that returns the current millisecond count from the system, but it might decrease. current-inexact-milliseconds is similar, but returns a guaranteed-to-increase floating point number. There are also a bunch of similar functions that you can find on that page, but if all you need is to time a certain function, then just … Read more
In DrRacket there is a SICP compatibility language 1. From the Package Manager In the documentation there is an easy guide to how it’s installed from DrRacket: Open the Package Manager: in DrRacket choose the menu “File” then choose “Package Manager…”. In the tab “Do What I Mean” find the text field and enter: “sicp” … Read more
You need to capture the state in some accumulators and update the state at each iteration. If you have experience in an imperative language, imagine writing a while loop and tracking information in variables during each iteration of the loop. What variables would you need? How would you update them? That’s exactly what you have … Read more
Use Racket (formerly PLT Scheme). The DrRacket IDE is an excellent starting point for all things Scheme including SICP. To look up keywords in the documentation, place the cursor on the keyword and press F1. In DrRacket you can now see the images directly in the REPL (the read-eval-print-loop). SICP Support for DrRacket, by Neil … Read more
You have several answers here, but none is really comprehensive (and I’m not talking about having enough details or being long enough). First of all, the bottom line: you should not use Common Lisp if you want to have a good experience with SICP. If you don’t know much Common Lisp, then just take it … Read more
new-if is a function. When a function is called, what’s the first thing that Scheme does with the argument list? It evaluates all the arguments.
This is a bit of a tricky question, since the differences are both technical and (more importantly, in my opinion) cultural. An answer can only ever provide an imprecise, subjective view. This is what I’m going to provide here. For some raw technical details, see the Scheme Wiki. Scheme is a language built on the … Read more