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More Simple Values

  • Simple values
    • Strings
    • Booleans and nil
    • Keywords

Simple values

We have already seen simple values that are numbers. Now we will take a closer look at simple values that are strings, booleans, and keywords.

Strings and characters

What is a string? A string is just a piece of text. To make a string, you enclose it in quotation marks.

"Hello world"
"This is a longer string that I wrote for purposes of an example."
"Aubrey said, \"I think we should go to the Orange Julius.\""

Look at the last example. A backslash is how we put a quotation mark inside a string. Do not try using single quotes to make a string.

Strings are made up of characters. You can make a single character by using a backslash, but we won't need to make individual characters for this course.

Booleans and nil

A boolean is a true or false value, and you type them just like that, true and false. Often in programming, we need to ask a true or false question, like "Is this class in the current semester?" or "Is this person's birthday today?" When we ask those questions, we get a boolean back.

There is another value like a boolean in some ways, but different. This value is nil, and it means no value at all. You will not often use this value yourself, but you may encounter it in other people's code.

EXERCISE: Store the name of your hometown

Write the name of your hometown as a string, and then assign that string to the name my-hometown.

EXERCISE: Make a function to format names

The str function can take any number of arguments, and it concatenates them together to make a string. Write a function called format-name that takes two arguments, first-name and last-name. This function should output the name like so: Last, First.