▼Unstable:   May Change Without Warning
►29 Syntax
On this page:
explode-module-path-index
phase-of-enclosing-module
make-variable-like-transformer
format-unique-id
syntax-within?
syntax-length
29.1 Syntax Object Source Locations
syntax-source-directory
syntax-source-file-name
6.2.1
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29 Syntax

Ryan Culpepper <ryanc@racket-lang.org>

This library is unstable; compatibility will not be maintained. See Unstable: May Change Without Warning for more information.

 (require unstable/syntax) package: base

procedure

(explode-module-path-index mpi)

 → (listof (or/c module-path? resolved-module-path? #f))
  mpi : module-path-index?
Unfolds mpi using module-path-index-split, returning a list of the relative module paths together with the terminal resolved module path or #f for the “self” module.

Examples:

> (explode-module-path-index (car (identifier-binding #'lambda)))

'("kw.rkt" "pre-base.rkt" "private/base.rkt" racket/base #f)

> (explode-module-path-index (caddr (identifier-binding #'lambda)))

'(racket/base #f)

> (explode-module-path-index (car (identifier-binding #'define-values)))

'('#%kernel #f)

syntax

(phase-of-enclosing-module)

Returns the phase level of the module in which the form occurs (and for the instantiation of the module in which the form is executed). For example, if a module is required directly by the “main” module (or the top level), its phase level is 0. If a module is required for-syntax by the “main” module (or the top level), its phase level is 1.

Examples:

> (module helper racket
    (require unstable/syntax)
    (displayln (phase-of-enclosing-module)))
> (require 'helper)

0

> (require (for-meta 1 'helper))

1

procedure

(make-variable-like-transformer reference-stx 
  [setter-stx]) 
 → set!-transformer?
  reference-stx : syntax?
  setter-stx : (or/c syntax? #f) = #f
Creates a transformer that replaces references to the macro identifier with reference-stx. Uses of the macro in operator position are interpreted as an application with reference-stx as the function and the arguments as given.

If the macro identifier is used as the target of a set! form, then the set! form expands into the application of setter-stx to the set! expression’s right-hand side, if setter-stx is syntax; otherwise, the identifier is considered immutable and a syntax error is raised.

Examples:

> (define the-box (box add1))
> (define-syntax op
    (make-variable-like-transformer
     #'(unbox the-box)
     #'(lambda (v) (set-box! the-box v))))
> (op 5)

6

> (set! op 0)
> op

0

The subsequent bindings were added by Vincent St-Amour <stamourv@racket-lang.org>.

procedure

(format-unique-id lctx    
  fmt    
  v ...    
  [#:source src    
  #:props props    
  #:cert cert]) → identifier?
  lctx : (or/c syntax? #f)
  fmt : string?
  v : (or/c string? symbol? identifier? keyword? char? number?)
  src : (or/c syntax? #f) = #f
  props : (or/c syntax? #f) = #f
  cert : (or/c syntax? #f) = #f
Like format-id, but returned identifiers are guaranteed to be unique.

procedure

(syntax-within? a b) → boolean?

  a : syntax?
  b : syntax?
Returns true is syntax a is within syntax b in the source. Bounds are inclusive.

The subsequent bindings were added by Eric Dobson <eric.n.dobson@gmail.com>.

procedure

(syntax-length stx) → exact-nonnegative-integer?

  stx : syntax?
Performs (length (syntax->list stx)).

Example:

> (syntax-length #'(d e f))

3

The subsequent bindings were added by Carl Eastlund <cce@racket-lang.org>.

29.1 Syntax Object Source Locations

procedure

(syntax-source-directory stx) → (or/c path? #f)

  stx : syntax?

procedure

(syntax-source-file-name stx) → (or/c path? #f)

  stx : syntax?
These produce the directory and file name, respectively, of the path with which stx is associated, or #f if stx is not associated with a path.

Examples:

(define loc
  (list (build-path "/tmp" "dir" "somewhere.rkt")
        #f #f #f #f))
(define stx1 (datum->syntax #f 'somewhere loc))
> (syntax-source-directory stx1)

#<path:/tmp/dir/>

> (syntax-source-file-name stx1)

#<path:somewhere.rkt>

(define stx2 (datum->syntax #f 'nowhere #f))
> (syntax-source-directory stx2)

#f

> (syntax-source-directory stx2)

#f

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