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Implicit renaming macros
This module contains some macros to make the use of low-level implicit renaming macros easyier. Recall that those macros are implemented as a transformer routine, which is a three-parameter procedure
(lambda (form inject compare?) ...)
which has to be enclosed by an ir-macro-transformer call. The programmer's job is to destructure the macro-code, form. All symbols of the macro-expression not protected by inject are transparently renamed in the background to achieve hygiene. If no symbol is injected, the macro is automatically hygienic.
The job of destructuring the macro-code is tedious and error prone, it can be done by a tool, match from the matchable egg, for example. The other job, compare? literal symbols with those renamed behind the scene, something which is needed to use literals like else and => in the cond macro, remains to be done.
ir-macro-rules[syntax] (ir-macro-rules (sym ...) (pat0 transformer0) (pat1 transformer1) ...)
where each sym ... will break hygiene, hence the list (sym ...) is usually empty. pat0 pat1 ... are patterns describing admissible macro-codes (the macro-name can be replaced by an underscore) and transformer0 transformer1 ... are corresponding macro-transformers, procedures of two arguments, usually named inject and compare?. The inject argument is still used in the rare occasions, where literal symbols are exported.
This macro is similar to and works like syntax-rules by design. That is, the macro-code is compared to pat0 pat1 in sequence and the transformer of the first matching pattern is executed. Nevertheless, there are two differences. First, the unrenamed symbols (sym ...) to be used in the transformers have nothing to do with literals like else and => in the cond macro (those are handled by compare?), and second, the patterns are not paired with templates as in syntax-rules, but with two-parameter procedures which generate those templates (usually in the form of quasiquoted lists which contain the symbols sym ... unquoted). This makes ir-macro-rules much more flexible than syntax-rules: The programmer has the freedom to decide what to do at compile-time and what at runtime.
macro-rules[syntax] (macro-rules (sym ...) (pat0 transformer0) (pat1 transformer1) ...)
Alias of ir-macro-rules.
ir-macro-define[syntax] (ir-macro-define (name . args) (lambda (inject compare? sym ...) . body))
defines a macro with macro-code (name . args) by means of a transformer, which is a procedure of inject, compare? and (rarely!) sym .... This is quite similar to the old define-macro of Chicken-3, where it not for the lambda line.
macro-define[syntax] (macro-define (name . args) (lambda (inect compare? sym ...) . body))
Alias of ir-macro-define
ir-macro-let[syntax] (ir-macro-let ((code0 transformer0) ...) . body)
where code0 ... is the macro-code (name0 . args0) ... of a local macro and transformer0 ... the corresponding transformer (lambda (inject compare? sym ...) . body0) .... These macros are locally defined in parallel and in there scope body is executed.
macro-let[syntax] (macro-let ((code0 transformer0) ...) . body)
Alias of ir-macro-let
ir-macro-letrec[syntax] (ir-macro-letrec ((code0 transformer0) ...) . body)
recursive version of ir-macro-let, i.e. the local macros have access to each other.
macro-letrec[syntax] (macro-letrec ((code0 transformer0) ...) . body)
Alias of ir-macro-letrec
(import-for-syntax (only matchable match) (only ir-macros ir-macro-rules))
(define-syntax my-or ; ok (ir-macro-rules () ((_) (lambda (insert compare?) #f)) ((_ arg . args) (lambda (insert compare?) `(if ,arg ,arg (my-or ,@args))))))
Copyright (c) 2011, Juergen Lorenz All rights reserved.
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- added additional inject argument to all transformers
- initial import