Scheme - Is there anyway for scheme to see ' as a symbol

Author

Is there anyway for scheme to see ' as a symbol

audibel

2004-11-01, 3:56 am

Reading from a text file...
I wrote a program to find an occurence of a string
in a text file, and I tested it on several text files, but Scheme has a
problem reading the ' character as a symbol. Any suggestions? The
program works great besides that... It took me AWHILE, but I finally got
it... Now if I could just get the bugs out... Are there any other
characters Scheme might not recognize as symbols that I should know about?

Jussi Piitulainen

2004-11-01, 8:56 am

audibel writes:

> Reading from a text file...
> I wrote a program to find an occurence of a string in a text file,
> and I tested it on several text files, but Scheme has a problem
> reading the ' character as a symbol. Any suggestions? The program
> works great besides that... It took me AWHILE, but I finally got
> it... Now if I could just get the bugs out... Are there any other
> characters Scheme might not recognize as symbols that I should know
> about?

You will have problems with all manner of lexical syntax if you read
with READ. READ is a parser. Characters include "',;() that certainly
occur in text, and also #`\ and probably [|]. Digits and and +-. put
you into number syntax and will cause problems.

Maybe you can preprocess the text so that problem cases are encoded
safely before you read them into Scheme. Better may be to write your
own reader and tokeniser; your implementation may provide at least
read-line to read a line as a string - it isn't hard to write - and
also tools to do things with strings.

You can, actually, turn ' into a symbol by (string->symbol "'") but I
suspect you would be better off working with strings.

audibel

2004-11-01, 8:57 pm

I didn't even think about numbers, the example texts I used both were small
white lists of hyperlinks, so most of the data was in one continious
string, thanks. My book uses read to read from a text file, so I thought
that would be the procedure to use. I'll look for a read line procedurce,
if not I assume I'll have to use a read-char to make my own read line,
which shouldn't be too hard.

One thing I noticed about my program and PLT Scheme in general that I
didn't like. I had Windows Task Manager (Yes, Computer Gods forgive me,
for right now I am using Windows) open and Plt Scheme is taking anywhere
from 50 - 80 megs of RAM??? The program binary for this little text grep
wannabe is sucking up about 7 megs of RAM??? Is that something I am doing
wrong in my code, or do Scheme programs usually suck system resources like
that? This isn't a huge file, we're talking probably less than 50 lines
of code.

Joe Marshall

2004-11-02, 3:58 pm

"audibel" <audibel@sbcglobal.net> writes:

> One thing I noticed about my program and PLT Scheme in general that I
> didn't like. I had Windows Task Manager (Yes, Computer Gods forgive me,
> for right now I am using Windows) open and Plt Scheme is taking anywhere
> from 50 - 80 megs of RAM??? The program binary for this little text grep
> wannabe is sucking up about 7 megs of RAM??? Is that something I am doing
> wrong in my code, or do Scheme programs usually suck system resources like
> that?

Are you saving it for something? 7 meg of physical RAM goes for about
a buck (SO-DIMM PC2100 DDR). Virtual memory costs less.

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