CSC 270 - Survey of Programming Languages: Scheme (Racket)

Symbolic Information

Representing Symbolic Information

Computers these days are expected to be able to process information such as names, words, and image.
Scheme supports symbols, strings, characters (from a keyboard) and images.
A symbol is a sequence of characters preceded by a forward quotation mark (also known as an apostrophe)
```
'the   'dog   'ate   'a   'chocolate   'cat! 'two^3
```
- Not every character is allowed in a symbol (e.g., blanks and commas). To include these in a symbol, use vertical bars e.g., '|Yesterday, I walked very far|
Symbols are handled as atomic data (not subdivided)

Symbols

Scheme provides one basic operation eq? which produces true if the two symbols match.

(eq? 'Hello x) = true is x stands for ':w
llo
(eq? 'Hello x) = false is x stands for 'Howdy

Symbols were introduced to programming as a way to have the computer reply to users. We could have the computer print an appropriate response to certain messages entered by users.

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