2.26 Importing Modules Lazily: lazy-require

The bindings documented in this section are provided by the racket/lazy-require library, not racket/base or racket.

syntax
(lazy-require [module-path (fun-import ...)] ...)

fun-import = fun-id
| (orig-fun-id fun-id)

Defines each fun-id as a function that, when called, dynamically requires the export named orig-fun-id from the module specified by module-path and calls it with the same arguments. If orig-fun-id is not given, it defaults to fun-id.

If the enclosing relative phase level is not 0, then module-path is also placed in a submodule (with a use of define-runtime-module-path-index at phase level 0 within the submodule). Introduced submodules have the names lazy-require-n-m, where n is a phase-level number and m is a number.

When the use of a lazily-required function triggers module loading, register-external-module declares a potential compilation dependency (in case the function is used in the process of compiling a module).

Examples:

> (lazy-require
    [racket/list (partition)])
> (partition even? '(1 2 3 4 5))
'(2 4)
'(1 3 5)
> (module hello racket/base
    (provide hello)
    (printf "starting hello server\n")
    (define (hello) (printf "hello!\n")))
> (lazy-require
    ['hello ([hello greet])])
> (greet)
starting hello server
hello!

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4	Structures
5	Classes and Objects
6	Units
7	Contracts
8	Pattern Matching
9	Control Flow
10	Concurrency and Parallelism
11	Macros
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13	Reflection and Security
14	Operating System
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	Index

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