15.3.4.1 Inspecting syntactic binding’s descriptors

We must remember that a syntactic binding’s descriptor is a pair with format:

(?binding-type . ?binding-value)

first let’s create an environment object with the system library:

(define env (environment '(psyntax system $all)))

then let’s look at some descriptors:

• Primitive function display:

  (define-values (label descriptor)
    (environment-binding 'display env))
  descriptor              ⇒ (core-prim . display)
  (symbol-value label)    ⇒ (core-prim . display)
  (eq? descriptor (symbol-value label))
  ⇒ #t
  

  in the descriptor: ?binding-type is the symbol ‘core-prim’ and ?binding-value is the symbol ‘display’, which is the public name of the primitive function.

• Core primitive syntax lambda:

  (define-values (label descriptor)
    (environment-binding 'lambda env))
  descriptor              ⇒ (core-macro . lambda)
  (symbol-value label)    ⇒ (core-macro . lambda)
  (eq? descriptor (symbol-value label))
  ⇒ #t
  

  in the descriptor: ?binding-type is the symbol ‘core-macro’ and ?binding-value is the symbol ‘lambda’, which is the public name of the primitive syntax.

• Non–core primitive syntax let:

  (define-values (label descriptor)
    (environment-binding 'let env))
  descriptor              ⇒ (macro . let)
  (symbol-value label)    ⇒ (macro . let)
  (eq? descriptor (symbol-value label))
  ⇒ #t
  

  in the descriptor: ?binding-type is the symbol ‘macro’ and ?binding-value is the symbol ‘let’, which is the public name of the primitive syntax.

• Condition object type &condition, which is implemented as R6RS record type:

  (define-values (label descriptor)
    (environment-binding '&condition env))
  descriptor
  ⇒ (core-object-type-name . (#<record-type-spec> .
    (&condition &condition-rtd &condition-rcd <condition>
       make-simple-condition condition? ())))
  
  (symbol-value label)
  ⇒ (core-object-type-name . (#<record-type-spec> .
    (&condition &condition-rtd &condition-rcd <condition>
       make-simple-condition condition? ())))
  
  (eq? descriptor (symbol-value label))
  ⇒ #t
  

  in the descriptor: ?binding-type is the symbol ‘core-object-type-name’ and ?binding-value is the list:

  (#<record-type-spec> .
    (&condition &condition-rtd &condition-rcd <condition>
       make-simple-condition condition? ()))
  

  we can further inspect &condition-rtd and &condition-rcd:

  (receive (label descriptor)
      (environment-binding '&condition-rtd env)
    descriptor)
  ⇒ ($core-rtd . &condition-rtd)
  
  (receive (label descriptor)
      (environment-binding '&condition-rcd env)
    descriptor)
  ⇒ ($core-rcd . &condition-rcd)