4.8 Keywords

► |  | The Racket Reference

1 | Language Model
2 | Notation for Documentation
3 | Syntactic Forms
4 | Datatypes
5 | Structures
6 | Classes and Objects
7 | Units
8 | Contracts
9 | Pattern Matching
10 | Control Flow
11 | Concurrency and Parallelism
12 | Macros
13 | Input and Output
14 | Reflection and Security
15 | Operating System
16 | Memory Management
17 | Unsafe Operations
18 | Running Racket
| Bibliography
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▼ | 4 | Datatypes

4.1 | Booleans and Equality
4.2 | Numbers
4.3 | Strings
4.4 | Byte Strings
4.5 | Characters
4.6 | Symbols
4.7 | Regular Expressions
4.8 | Keywords
4.9 | Pairs and Lists
4.10 | Mutable Pairs and Lists
4.11 | Vectors
4.12 | Boxes
4.13 | Hash Tables
4.14 | Sequences and Streams
4.15 | Dictionaries
4.16 | Sets
4.17 | Procedures
4.18 | Void
4.19 | Undefined

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keyword?
keyword->string
string->keyword
keyword<?

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#### 4.8`` Keywords

> > > Keywords in The Racket Guide introduces keywords.

A keyword is like an interned symbol, but its printed form starts with #:, and a keyword cannot be used as an identifier. Furthermore, a keyword by itself is not a valid expression, though a keyword can be quoted to form an expression that produces the symbol.

Two keywords are eq? if and only if they print the same (i.e., keywords are always interned).

Like symbols, keywords are only weakly held by the internal keyword table; see Symbols for more information.

See Reading Keywords for information on reading keywords and Printing Keywords for information on printing keywords.

> procedure (keyword? v) → boolean?
> v : any/c

Returns #t if v is a keyword, #f otherwise.

> procedure (keyword->string keyword) → string?
> keyword : keyword?

Returns a string for the displayed form of keyword, not including the leading #:.

> procedure (string->keyword str) → keyword?
> str : string?

Returns a keyword whose displayed form is the same as that of str, but with a leading #:.

> procedure (keyword<? a-keyword b-keyword ...+) → boolean?
> a-keyword : keyword?
> b-keyword : keyword?

Returns #t if the arguments are sorted, where the comparison for each pair of keywords is the same as using keyword->string with string->bytes/utf-8 and bytes<?.
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