Racket Basic Data Types
Numbers
Any kind of number. Racket makes no distinction between integers, real numbers, rationals, etc. Literal representations match what you are used to from math and from other programming languages.
| Operations | Description |
|---|---|
number? |
type predicate - returns true if argument is a number |
zero? |
test if argument is zero |
=, <, <=,
>, >=
|
comparison operators |
+, -, *, /, etc. |
standard arithmetic operations |
Booleans
Two possible values: #t for true and #f
for false.
| Operations | Description |
|---|---|
boolean? |
type predicate |
eq? |
equality test |
and, or, not |
standard boolean operators |
Symbols
An identifier that is used as a value. We must "quote" the
identifier so the interpreter knows not to evaluate the identifier.
This is done either as (quote blue) or
'blue.
| Operations | Description |
|---|---|
symbol? |
type predicate |
eq? |
equality test |
and, or, not |
standard boolean operators |
Characters
For printable literals: precede with a #\. For
example, #\a is the character 'a'.
For nonprintable literals: use the character's name preceded by
#\. For example, #\space and
#\newline are the space and newline characters.
| Operations | Description |
|---|---|
char? |
type predicate |
char-alphabetic?, char-numeric?,
char-whitespace?
|
determine the type of the character |
char=?,
char<?, char<=?,
char>?, char>=?
|
comparison operators |
char->integer |
return the ASCII value of a character |
Strings
A sequence of characters surrounded by double quotes ("").
| Operations | Description |
|---|---|
string? |
type predicate |
string=?,
string<?, string<=?,
string>?, string>=?
|
comparison operators |
string-ci=?,
string-ci<?, string-ci<=?,
string-ci>?, string-ci>=?
|
case-insensitive comparison operators |
string-length |
return length of a string/td> |
string-ref |
returns the character at given index:(string-ref "Eugene" 0)
|
string-append |
concatenate two strings to create a new string |
string->list,
string->symbol,
string->number
|
convert a string to another type |
string |
create a string from zero or more characters |