Error Messages

Believe it or not, but the error messages that you get from DrRacket occasionally contain useful information. (Okay, the always contain useful information. It may just be difficult to comprehend the information.) Read the emssages. If they make sense, follow up on the error. If they don't, check this reference or ask for help (or both).

Here are some of the more confusing error messages you might receive and a possible explanation of those error messages. If you get other error messages, please send them to <rebelsky@grinnell.edu> and your faculty member so that we can add explanations to the list.

Missing gigls

./../opt/racket/collects/mred/private/snipfile.rkt:324:2: open-input-file: 
cannot open input file
  path: /glimmer/lib/gigls/unsafe.rkt
    system error: No such file or directory; errno=2

Although we do our best to have gigls installed on every computer in MathLAN, some get missed (e.g., because they were off when we attempted to install gigls). Email the name of the computer to <rebelsky@grinnell.edu> and move to another computer.

Bad Version

../../usr/share/racket/collects/errortrace/errortrace-lib.rkt:399:2:
load-extension: bad version 5.3.6@3m (not 5.2.1@3m) from
"/glimmer/lib/louDBus/compiled/native/x86_64-linux/3m/loudbus.so"

We have two versions of DrRacket installed on the computers. This message suggests that you are running the older version. Make sure that your launcher is configured to use the newer version, which is in /opt/racket/bin/drracket. If you don't know how to configure your launcher, get help from a tutor, mentor, faculty member, or perhaps even just an upper-level CS student. (Instructions are in the Linux lab.)

Unbound Identifiers

drawing-XXX: unbound identifier in module in: drawing-XXX

If the unbound identifier is one of the MediaScheme/gigls procedures, you probably forgotten to include (require gigls/unsafe) in the top of the definitions pane. If the unbound identifier is not one of those procedures, it just means that you forgot to define it. (When we use define to associate a name with a value, Scheme says that the name (identifier) is “bound”.)

Can't Render Drawings

. . ../../rebelsky/share/lib/gigls/drawings.rkt:1130:7: 
 drawing-render!: Drawing does not fit within image bounds (image-width: 275 
 image-height: 184 drawing-left: 9453.0 drawing-top: 4231.875 drawing-right: 
 9591.0 drawing-bottom: 4324.375)

You will get an error message like this if you use drawing->image or drawing-render! and the drawing you are using is outside the bounds of the of the coresponding image. In this particular instance, since the image is 275 wide, the left edge of the drawing has to be smaller than 275. It's not. It's 9453, which is much larger.

Not a Procedure

application: not a procedure;
 expected a procedure that can be applied to arguments
   given: 3
     arguments...:

This error message suggests that you have something other than a procedure immediately after an open parenthesis. (Many of us are tempted to parenthesize parameters and such. Scheme gets upset when you do that.)