How to import files relative to main file, instead of current directory? ((Chez) Scheme)

Question

For example, in my main.scm file I have (load "util.scm"). util.scm is a file in the same folder as main.scm. Both files are located in ~/documents/myproject/.

Now when I'm in this directory, and I run $ chez-scheme main.scm everything works fine. However, if I'm in my home directory and run $chez-scheme documents/myproject/main.scm it complains, not being able to find the file util.scm. I suppose this is the case because the current directory was my relevant home directory, and as such util.scm is indeed not there, it is actually in documents/myproject/. That being said, I'm used (in other languages) to the functionality of looking these paths up relative to the file containing the instruction to import, and I'd like to have that here as well. I've tried prefixing it by ./ or defining the file as a libary and doing (import (util)) but none of it works outside of documents/myproject/. Is there any way to get this to work as I intend it to?

I assume this is Chez-Scheme-specific. If not I'd prefer an answer that is implementation-neutral.

Answer 1

load is kind of awkward in R5RS since the report states that system interfaces are off topic in the report, but they include load which is a half hearted solution. The report does not say if the load is relative to the current directory or the file the load form originates from so in order to be portable I guess you are required to run your script from the current directory and have your loaded file relative to both.

Since Chez Scheme implements R6RS load is not really the right form to use. R6RS removed load in favor of libraries. You should make your file a library and consult how to install it. In some systems that is just placing the files in the right path, adding library location in configuration or running install script. How one uses the library is the same in all implementations, by using import.

According to Chez documentation you can pass --libdirs to it to give it one or more paths to consider for loading libraries. You can see the paths it scans by evaluating (library-directories)

Answer 2

There are several different ways to accomplish what (I think) you are trying to do, but eventually they all boil down to letting Chez know where to look for things. When given relative paths, include and load use the source-directories parameter to search for the requested file. Libraries have their path automatically prepended to source-directories while they are being loaded or compiled, so if your main.scm were a library definition then it would find util.scm as you expect.

However, it sounds like main.scm isn't a library, it's a top-level program. Unfortunately, Chez doesn't have a command line option to set the source-directories like it does for library directories. That leaves you with a bit less flexibility. Any of the following will work:

• Make util.scm a library and invoke Chez with the --libdirs option to let it know where to look for libraries.
• Set source-directories and load main.scm from inside the REPL rather than from the command line.
• Write a wrapper shell script that does the above by echoing the commands into scheme so you don't have to type it yourself. (Only suitable if you don't also need to then type into the scheme session).
• Write a wrapper shell script that cds into your project directory before running scheme (and presumably cds back to the original directory when it's done).