3 Syntactic Forms

► |  | 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
| Index

▼ | 3 | Syntactic Forms

3.1 | Modules: module, module*, ...
3.2 | Importing and Exporting: require and provide
3.3 | Literals: quote and #%datum
3.4 | Expression Wrapper: #%expression
3.5 | Variable References and #%top
3.6 | Locations: #%variable-reference
3.7 | Procedure Applications and #%app
3.8 | Procedure Expressions: lambda and case-lambda
3.9 | Local Binding: let, let*, letrec, ...
3.10 | Local Definitions: local
3.11 | Constructing Graphs: shared
3.12 | Conditionals: if, cond, and, and or
3.13 | Dispatch: case
3.14 | Definitions: define, define-syntax, ...
3.15 | Sequencing: begin, begin0, and begin-for-syntax
3.16 | Guarded Evaluation: when and unless
3.17 | Assignment: set! and set!-values
3.18 | Iterations and Comprehensions: for, for/ list, ...
3.19 | Continuation Marks: with-continuation-mark
3.20 | Quasiquoting: quasiquote, unquote, and unquote-splicing
3.21 | Syntax Quoting: quote-syntax
3.22 | Interaction Wrapper: #%top-interaction
3.23 | Blocks: block
3.24 | Internal-Definition Limiting: #%stratified-body
3.25 | Performance Hints: begin-encourage-inline
3.26 | Importing Modules Lazily: lazy-require

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### 3`` Syntactic Forms

This section describes the core syntax forms that appear in a fully expanded expression, plus many closely related non-core forms. See Fully Expanded Programs for the core grammar.

3.1 Modules: module, module*, ...
3.2 Importing and Exporting: require and provide
3.2.1 Additional require Forms
3.2.2 Additional provide Forms
3.3 Literals: quote and #%datum
3.4 Expression Wrapper: #%expression
3.5 Variable References and #%top
3.6 Locations: #%variable-reference
3.7 Procedure Applications and #%app
3.8 Procedure Expressions: lambda and case-lambda
3.9 Local Binding: let, let*, letrec, ...
3.10 Local Definitions: local
3.11 Constructing Graphs: shared
3.12 Conditionals: if, cond, and, and or
3.13 Dispatch: case
3.14 Definitions: define, define-syntax, ...
3.14.1 require Macros
3.14.2 provide Macros
3.15 Sequencing: begin, begin0, and begin-for-syntax
3.16 Guarded Evaluation: when and unless
3.17 Assignment: set! and set!-values
3.18 Iterations and Comprehensions: for, for/list, ...
3.18.1 Iteration and Comprehension Forms
3.18.2 Deriving New Iteration Forms
3.18.3 Do Loops
3.19 Continuation Marks: with-continuation-mark
3.20 Quasiquoting: quasiquote, unquote, and unquote-splicing
3.21 Syntax Quoting: quote-syntax
3.22 Interaction Wrapper: #%top-interaction
3.23 Blocks: block
3.24 Internal-Definition Limiting: #%stratified-body
3.25 Performance Hints: begin-encourage-inline
3.26 Importing Modules Lazily: lazy-require

Notation

Each syntactic form is described by a BNF-like notation that describes a combination of (syntax-wrapped) pairs, symbols, and other data (not a sequence of characters). These grammatical specifications are shown as in the following specification of a something form:

> > (something id thing-expr ...)
> > | thing-expr |  | : |  | number?

Within such specifications,

- ... indicates zero or more repetitions of the preceding datum; more generally, N consecutive ...s a row indicate a consecutive repetition of the preceding N datums.

- ...+ indicates one or more repetitions of the preceding datum.

- Italic meta-identifiers play the role of non-terminals. Some meta-identifier names imply syntactic constraints:

  - A meta-identifier that ends in id stands for an identifier.

  - A meta-identifier that ends in keyword stands for a keyword.

  - A meta-identifier that ends with expr (such as thing-expr) stands for a sub-form that is expanded as an expression.

  - A meta-identifier that ends with body stands for a sub-form that is expanded in an internal-definition context (see Internal Definitions).

- Contracts indicate constraints on sub-expression results. For example, thing-expr : number? indicates that the expression thing-expr must produce a number.

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