Re: use variable out side procedure

[Aaron Hill]

On 2020-05-29 6:49 am, Freeman Gilmore wrote:
> I guess i need a text/course book in scheme that explained little
> things like that.   That was simple, thank you, ƒg

Might I recommend the following:

================================

- "The Little Schemer" [1]
    Daniel P. Friedman, Matthias Felleisen

This work builds on Friedman's original "The Little LISPer" which 
features a very unique way of explaining a programming language.  The 
book presents information in a two-column format with questions on the 
left and answers on the right.  Each pair of question and answer either 
introduces a new concept or further refines a prior one.  The student is 
encouraged to read the work one question and answer at a time, spending 
time to ensure they understand why an answer makes sense before moving 
onto the next question.  Building on the information learned, a student 
can attempt to infer the answer to a question before reading the printed 
one for confirmation or correction.

Plus, the book has illustrations of elephants.

After you have finished, there are two follow-ups for consideration:

- "The Seasoned Schemer" [2]
    Daniel P. Friedman, Matthias Felleisen
- "The Reasoned Schemer" [3]
    Daniel P. Friedman, William E. Byrd,
    Oleg Kiselyov, Jason Hemann

[1]: https://mitpress.mit.edu/books/little-schemer-fourth-edition
[2]: https://mitpress.mit.edu/books/seasoned-schemer-second-edition
[3]: https://mitpress.mit.edu/books/reasoned-schemer-second-edition

================================

- "How to Design Programs" [4]
    Matthias Felleisen, Robert Bruce Findler,
    Matthew Flatt, Shriram Krishnamurthi

Compared to "The Little Schemer", this work is presented in a more 
traditional manner.  While the book uses Racket [5] (formerly PLT 
Scheme) for demonstration, the intention is teaching principles of 
program design that are applicable to any language.

Of note, MIT Press has made this work available online for free [6].

[4]: https://mitpress.mit.edu/books/how-design-programs-second-edition
[5]: https://racket-lang.org/
[6]: https://htdp.org/


-- Aaron Hill