[plt-scheme] Some things about the Vector type that are not mentioned in normal documention

From: Devlin Bentley (com2kid at gmail.com)
Date: Sat Nov 27 16:19:42 EST 2004

As a new user to Scheme, I recently tried to implement a 2D array as a
vector of vectors in PltScheme.  Obviously things did not go well for
me (I used Make-Vector and I filled the vector with another set of

Now nowheres in the included documentation, t-y-scheme or the PLT
MzScheme language manual, is anything mentioned about this being an,
...., issue.  Actually I still have no idea exactly what happened,
something to do with graphs (they are mentioned once or twice in small
print in connection with Vectors) but still, there was definitely an

The thing is, the most straight forward way to create a 2D array (well
aside from the rather excellent SRFI 25 which has insanely nice
notation) for a student who has just been told to "use vectors like
arrays", is to make a vector of vectors.  From the students point of
view (looking at a vector as being a renamed array, which is not so
far off after they have taken linear algebra courses), this is
logically valid, and trying to debug what appears to be logically
valid code is rather hard!

The short of it is, it would be nice if something was mentioned in at
least one of the manuals telling the poor user "Not To Do That".

(I'd ask what the heck happened, but I am sure that will be covered in
my 2nd quarter of functional programming, but if anyone wants to hit
me with a clueX4 so I know what to expect when it does come up.... )
Devlin Bentley
Com2Kid at gmail.com

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