2 Syntactic Forms

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2 | Syntactic Forms
3 | Datatypes
4 | Structures
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6 | Units
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10 | Concurrency and Parallelism
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▼ | 2 | Syntactic Forms

2.1 | Modules: module, module*, ...
2.2 | Importing and Exporting: require and provide
2.3 | Literals: quote and #%datum
2.4 | Expression Wrapper: #%expression
2.5 | Variable References and #%top
2.6 | Locations: #%variable-reference
2.7 | Procedure Applications and #%app
2.8 | Procedure Expressions: lambda and case-lambda
2.9 | Local Binding: let, let*, letrec, ...
2.10 | Local Definitions: local
2.11 | Constructing Graphs: shared
2.12 | Conditionals: if, cond, and, and or
2.13 | Dispatch: case
2.14 | Definitions: define, define-syntax, ...
2.15 | Sequencing: begin, begin0, and begin-for-syntax
2.16 | Guarded Evaluation: when and unless
2.17 | Assignment: set! and set!-values
2.18 | Iterations and Comprehensions: for, for/ list, ...
2.19 | Continuation Marks: with-continuation-mark
2.20 | Quasiquoting: quasiquote, unquote, and unquote-splicing
2.21 | Syntax Quoting: quote-syntax
2.22 | Interaction Wrapper: #%top-interaction
2.23 | Blocks: block
2.24 | Internal-Definition Limiting: #%stratified-body
2.25 | Performance Hints: begin-encourage-inline
2.26 | Importing Modules Lazily: lazy-require

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### 2`` 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.

2.1 Modules: module, module*, ...
2.2 Importing and Exporting: require and provide
2.2.1 Additional require Forms
2.2.2 Additional provide Forms
2.3 Literals: quote and #%datum
2.4 Expression Wrapper: #%expression
2.5 Variable References and #%top
2.6 Locations: #%variable-reference
2.7 Procedure Applications and #%app
2.8 Procedure Expressions: lambda and case-lambda
2.9 Local Binding: let, let*, letrec, ...
2.10 Local Definitions: local
2.11 Constructing Graphs: shared
2.12 Conditionals: if, cond, and, and or
2.13 Dispatch: case
2.14 Definitions: define, define-syntax, ...
2.14.1 require Macros
2.14.2 provide Macros
2.15 Sequencing: begin, begin0, and begin-for-syntax
2.16 Guarded Evaluation: when and unless
2.17 Assignment: set! and set!-values
2.18 Iterations and Comprehensions: for, for/list, ...
2.18.1 Iteration and Comprehension Forms
2.18.2 Deriving New Iteration Forms
2.18.3 Do Loops
2.19 Continuation Marks: with-continuation-mark
2.20 Quasiquoting: quasiquote, unquote, and unquote-splicing
2.21 Syntax Quoting: quote-syntax
2.22 Interaction Wrapper: #%top-interaction
2.23 Blocks: block
2.24 Internal-Definition Limiting: #%stratified-body
2.25 Performance Hints: begin-encourage-inline
2.26 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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