Hey i'm just trying to write some code in DrScheme: ((function (x) (* x x)) 2) but i got a message saying: reference to undefined identifier: function I'm using language "Essentials of Programming languages (3rd ed.)" and the version of DrScheme is 4.2.1 Thanks! ...
I am just learning scheme, but I would love to be able to repeat myself less. Is there a way I can assign a name to a subexpression in the local scope? As per the comment: Haskell where clause x = s * t where s = 10 t = 20 x should be 200 in this case. ...
which data structure to use to sort n numbers in dr scheme i m not allowed to use vector and structure ..if i use list i cant edit the list values .so how can i sort n numbers . the language i use is textual mzscheme rsr5 ...
I am amazed by the "error" function in PLTScheme. If I have a division by zero, it doesnt do any other recursion and just comes out of the call stack and give me an error. Is there an implicit continuation before all the functions? Does the error throw away the call stack? Does anybody have any idea about this? ...
Is there a simpler way of writing in scheme (eqv? (regexp-match "0x" "0x1234") #t) #f (eqv? (regexp-match "0x" "1234") #f) #t ...
(define (read-all-input) (local ((define line (bytes->list (read-bytes 4)))) (if (eof-object? line) empty (cons line (read-all-input))))) (void (read-all-input)) The above code fails because bytes->list expects an argument of type byte string, but is given # ...
Hello, Now I'm following one more friend and now I started to learn PLT Scheme(using DrScheme), but I and my friends normally help each other in some projects, to do this we use revision controllers(normally SVN, in sometimes we use git), but which is the best revision control to use with PLT Scheme? Thanks. ...
Hello, I'm learning PLT Scheme and I want to know how can I build a Teach Pack for DrScheme, some tutorials...? Thanks. ...
I'm trying to make a truth-table generator for a digital electronics course because that's how I have fun in my spare time and don't judge me. Anywho, I figured I'd have a hash with the string equivalent of operators as keys, and the Scheme procedures that correspond to those operators as values. E.g. (define operator-table #hash(("...
I realize this is a total n00b question, but I'm curious and I thought I might get a better explanation here than anywhere else. Here's a list (I'm using Dr. Scheme) > (list 1 2 3) (1 2 3) Which I think is just sugar for this: > (cons 1 (cons 2 (cons 3 null))) (1 2 3) This, on the other hand, does something else: > (cons 1 (cons ...
Hi, using the PLT-Scheme-FFI, I want to call the C-function unsigned long mysql_real_escape_string(MYSQL *con, char *to, const char *from, unsigned long length) from a scheme procedure and continue using the resulting string 'to' inside the caller. The call of the scheme procedure would go like this: (define-values (to) (escape-str...
I heard that you can compile .ss files with DrScheme, and even remember doing it once to result in some good speedups on my code, since it doesn't need to put in all the debugging info necessary for the GUI. How does one go about doing this? ...
I can do it in Java, Python, Haskell... how do you do it in DrScheme? A customary google search didn't yield the answer. ...
(read) takes in a string from stdin, parses it as an s-expression, and returns that expression. How do I do the exact same thing, except taking input from a file? ...
How do I detect what command line arguments where given when a script is run with mred? That is, the equivalent of sys.argv in Python, args[] in Java, etc... ...
From the Plt-Scheme installation I have an example of C/Scheme interaction. There are two files: curses.c and curses-demo.ss. These files are available here. I've compiled curses.c, and trying to run curses-demo.ss And I am getting the following error: "put: expects argument of type 'character, string, or byte string'; given "Hello Worl...
Is there a for loop or for each loop in Scheme ? I've been searching around and found there is a keyword "every" but the scheme compiler language I'm using does not have this function pre-build in. This is what it suppose to do, it can be find here (define (first-letters sent) (every first sent)) > (first-letters '(here comes the su...
Assume I have a such struct: (define-struct node (value next)) ;and making 2 nodes, parent pointing to child as next. (define child (make-node 2 null)) (define parent (make-node 1 child)) Under PLT Scheme, while having child in my hand (and not knowing that parent is the pointer), is it possible to find the pointing node sctuct with...
All, In your mind, what are the pros and cons of using MIT Scheme versus DrScheme, in the context of trying to go through SICP (presumably simultaneously to watching some / all the MIT 6.001 videos)? Please feel free to edit below: MIT Scheme pros: - Specifically built for SICP and MIT 6.001. MIT Scheme cons: DrScheme pros: - Wid...
Hello, When you compile something written in PLT Scheme on Linux that have a GUI the final will be in a grey(default) theme of Linux, but I want to know If it's possible to integrate PLT Scheme with GTK or Qt? How to do this? Example of grey(default) theme: Thanks. ...