6b16679b39
The `lazy-require' form expands to `define-runtime-module-path-index', whch doesn't work right at phase levels other than 0. Work around the problem by generating a submodule to hold the `define-runtime-module-path-index' form. This repair fixes `raco exe' on certain uses of `match', which in turn uses `lazy-require' at compile time. Also, use `register-external-module' to generate appropriate dependencies on lazily loaded modules.
66 lines
2.7 KiB
Racket
66 lines
2.7 KiB
Racket
#lang scribble/manual
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@(require scribble/eval
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"utils.rkt"
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(for-label racket/base
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racket/runtime-path
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unstable/lazy-require
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compiler/cm-accomplice))
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@title[#:tag "lazy-require"]{Lazy Require}
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@unstable[@author+email["Ryan Culpepper" "ryanc@racket-lang.org"]]
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@defmodule[unstable/lazy-require]
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@defform/subs[#:literals (unquote)
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(lazy-require maybe-requires
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[mod (imported-fun-id ...)] ...)
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([mod module-path
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(unquote module-path-expr)]
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[maybe-requires code:blank
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(code:line #:requires-for-path (require-spec ...))])
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#:contracts ([module-path-expr module-path?])]{
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Defines each @racket[imported-fun-id] as a function that, when called,
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dynamically requires the export named @racket['imported-fun-id] from
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the module specified by @racket[mod] and calls it with the same
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arguments.
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The module @racket[mod] can be specified as a @racket[_module-path]
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(see @racket[require]) or as an @racket[unquote]-escaped expression
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that computes a module path. As with
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@racket[define-runtime-module-path-index], a @racket[module-path-expr]
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is evaluated both in phase level 0 and phase level 1 relative to its
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enclosing phase level.
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If the enclosing relative phase level is not 0, then
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@racket[module-path-expr] is also placed in a submodule (with a use of
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@racket[define-runtime-module-path-index] at phase level 0 within the
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submodule); supply extra @racket[require-spec]s with
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@racket[#:requires-for-path] to bind within the submodule for
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@racket[module-path-expr]. Introduced submodules have the names
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@racket[lazy-require-]@racket[_n]@racketidfont{-}@racket[_m], where
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@racket[_n] is a phase-level number and @racket[_m] is a number.
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When the use of a lazily-required function triggers module loading,
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@racket[register-external-module] declares a potential compilation
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dependency (in case the function is used in the process of compiling a
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module).}
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@defform[(begin-on-demand #:export (fun-id ...)
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body ...+)]{
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Defines each @racket[fun-id] as a function that, when called,
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dynamically loads and executes the @racket[body] forms. The
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@racket[body] forms must contain definitions for each @racket[fun-id],
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and the value of each @racket[fun-id] must be a function.
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A @racket[body] form may be any module-level form except
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@racket[provide]. In particular, @racket[require] forms are allowed.
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The @racket[body] forms are placed within a submodule that extends the
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scope of the enclosing module (ie, @racket[module*] with @racket[#f]
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in the language position). Consequently, any references to sibling
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submodules must include a with @racket[".."] module path element.
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}
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