MBOL)
            ((and (list? name)
                  (= (length name) 2)
                  (eq? (car name) 'unquote))
             (let ((doc (try-value-help (cadr name)
                                        (module-ref (current-module)
                                                    (cadr name)))))
               (cond ((not doc) (not-found 'documentation (cadr name)))
                     ((eq? doc #t)) ;; pass
                     (else (write-line doc)))))

            ;; (quote SYMBOL)
            ((and (list? name)
                  (= (length name) 2)
                  (eq? (car name) 'quote)
                  (symbol? (cadr name)))
             (cond ((search-documentation-files (cadr name))
                    => write-line)
                   (else (not-found 'documentation (cadr name)))))

            ;; (SYM1 SYM2 ...)
            ((and (list? name)
                  (and-map symbol? name)
                  (not (null? name))
                  (not (eq? (car name) 'quote)))
             (cond ((module-commentary name)
                    => (lambda (doc)
                         (display name) (write-line " commentary:")
                         (write-line doc)))
                   (else (not-found 'commentary name))))

            ;; unrecognized
            (else
             (help-usage)))
           '(begin)))))

(define (module-filename name)          ; fixme: better way? / done elsewhere?
  (let* ((name (map symbol->string name))
         (reverse-name (reverse name))
	 (leaf (car reverse-name))
	 (dir-hint-module-name (reverse (cdr reverse-name)))
	 (dir-hint (apply string-append
                          (map (lambda (elt)
                                 (string-append elt "/"))
                               dir-hint-module-name))))
    (%search-load-path (in-vicinity dir-hint leaf))))

(define (module-commentary name)
  (cond ((module-filename name) => file-commentary)
        (else #f)))

(define (help-doc term regexp)
  (let ((entries (apropos-fold (lambda (module name object data)
				 (cons (list module
					     name
					     (try-value-help name object)
					     (cond ((procedure? object)
						    "a procedure")
						   (else
						    "an object")))
				       data))
			       '()
			       regexp
			       apropos-fold-exported))
	(module car)
	(name cadr)
	(doc caddr)
	(type cadddr))
    (cond ((not (null? entries))
           (let ((first? #t)
                 (undocumented-entries '())
                 (documented-entries '())
                 (documentations '()))

             (for-each (lambda (entry)
                         (let ((entry-summary (simple-format
                                               #f "~S: ~S\n"
                                               (module-name (module entry))
                                               (name entry))))
                           (if (doc entry)
                               (begin
                                 (set! documented-entries
                                       (cons entry-summary documented-entries))
                                 ;; *fixme*: Use `describe' when we have GOOPS?
                                 (set! documentations
                                       (cons (simple-format
                                              #f "`~S' is ~A in the ~S module.\n\n~A\n"
                                              (name entry)
                                              (type entry)
                                              (module-name (module entry))
                                              (doc entry))
                                             documentations)))
                               (set! undocumented-entries
                                     (cons entry-summary
                                           undocumented-entries)))))
                       entries)

             (if (and (not (null? documented-entries))
                      (or (> (length documented-entries) 1)
                          (not (null? undocumented-entries))))
                 (begin
                   (display "Documentation found for:\n")
                   (for-each (lambda (entry) (display entry))
                             documented-entries)
                   (set! first? #f)))

             (for-each (lambda (entry)
                         (if first?
                             (set! first? #f)
                             (newline))
                         (display entry))
                       documentations)

             (if (not (null? undocumented-entries))
                 (begin
                   (if first?
                       (set! first? #f)
                       (newline))
                   (display "No documentation found for:\n")
                   (for-each (lambda (entry) (display entry))
                             undocumented-entries)))))
          ((search-documentation-files term)
           => (lambda (doc)
                (write-line "Documentation from file:")
                (write-line doc)))
          (else
           ;; no matches
           (display "Did not find any object ")
           (simple-format #t
                          (if (symbol? term)
                              "named `~A'\n"
                              "matching regexp \"~A\"\n")
                          term)))))

(define (help-usage)
  (display "Usage: (help NAME) gives documentation about objects named NAME (a symbol)
       (help REGEXP) ditto for objects with names matching REGEXP (a string)
       (help 'NAME) gives documentation for NAME, even if it is not an object
       (help ,EXPR) gives documentation for object returned by EXPR
       (help (my module)) gives module commentary for `(my module)'
       (help) gives this text

`help' searches among bindings exported from loaded modules, while
`apropos' searches among bindings visible from the \"current\" module.

Examples: (help help)
          (help cons)
          (help \"output-string\")

Other useful sources of helpful information:

(apropos STRING)
(arity PROCEDURE)
(name PROCEDURE-OR-MACRO)
(source PROCEDURE-OR-MACRO)

Tools:

(backtrace)				;show backtrace from last error
(debug)					;enter the debugger
(trace [PROCEDURE])			;trace procedure (no arg => show)
(untrace [PROCEDURE])			;untrace (no arg => untrace all)

(OPTIONSET-options 'full)		;display option information
(OPTIONSET-enable 'OPTION)
(OPTIONSET-disable 'OPTION)
(OPTIONSET-set! OPTION VALUE)

where OPTIONSET is one of debug, read, eval, print

"))

;;; {Apropos}
;;;
;;; Author: Roland Orre <orre@nada.kth.se>
;;;

;; Two arguments: the module, and the pattern, as a string.
;;
(define apropos-hook (make-hook 2))

(define (apropos rgx . options)
  "Search for bindings: apropos regexp {options= 'full 'shadow 'value}"
  (run-hook apropos-hook (current-module) rgx)
  (if (zero? (string-length rgx))
      "Empty string not allowed"
      (let* ((match (make-regexp rgx))
	     (uses (module-uses (current-module)))
	     (modules (cons (current-module)
			    (if (and (not (null? uses))
				     (eq? (module-name (car uses))
					  'duplicates))
				(cdr uses)
				uses)))
	     (separator #\tab)
	     (shadow (member 'shadow options))
	     (value (member 'value options)))
	(cond ((member 'full options)
	       (set! shadow #t)
	       (set! value #t)))
	(for-each
	 (lambda (module)
	   (let* ((name (module-name module))
		  (obarray (module-obarray module)))
	     ;; XXX - should use hash-fold here
	     (hash-for-each
	      (lambda (symbol variable)
		(cond ((regexp-exec match (symbol->string symbol))
		       (display name)
		       (display ": ")
		       (display symbol)
		       (cond ((variable-bound? variable)
			      (let ((val (variable-ref variable)))
				(cond ((or (procedure? val) value)
				       (display separator)
				       (display val)))))
			     (else
			      (display separator)
			      (display "(unbound)")))
		       (if (and shadow
				(not (eq? (module-ref module symbol)
					  (module-ref (current-module) symbol))))
			   (display " shadowed"))
		       (newline))))
	      obarray)))
	 modules))))

(define (apropos-internal rgx)
  "Return a list of accessible variable names."
  (apropos-fold (lambda (module name var data)
		  (cons name data))
		'()
		rgx
		(apropos-fold-accessible (current-module))))

(define (apropos-fold proc init rgx folder)
  "Folds PROCEDURE over bindings matching third arg REGEXP.

Result is

  (PROCEDURE MODULE1 NAME1 VALUE1
    (PROCEDURE MODULE2 NAME2 VALUE2
      ...
      (PROCEDURE MODULEn NAMEn VALUEn INIT)))

where INIT is the second arg to `apropos-fold'.

Fourth arg FOLDER is one of

  (apropos-fold-accessible MODULE) ;fold over bindings accessible in MODULE
  apropos-fold-exported		   ;fold over all exported bindings
  apropos-fold-all		   ;fold over all bindings"
  (run-hook apropos-hook (current-module) rgx)
  (let ((match (make-regexp rgx))
	(recorded (make-hash-table)))
    (let ((fold-module
	   (lambda (module data)
	     (let* ((obarray-filter
		     (lambda (name val data)
		       (if (and (regexp-exec match (symbol->string name))
				(not (hashq-get-handle recorded name)))
			   (begin
			     (hashq-set! recorded name #t)
			     (proc module name val data))
			   data)))
		    (module-filter
		     (lambda (name var data)
		       (if (variable-bound? var)
			   (obarray-filter name (variable-ref var) data)
			   data))))
	       (cond (module (hash-fold module-filter
					data
					(module-obarray module)))
		     (else data))))))
      (folder fold-module init))))

(define (make-fold-modules init-thunk traverse extract)
  "Return procedure capable of traversing a forest of modules.
The forest traversed is the image of the forest generated by root
modules returned by INIT-THUNK and the generator TRAVERSE.
It is an image under the mapping EXTRACT."
  (lambda (fold-module init)
    (let* ((table (make-hash-table))
	   (first? (lambda (obj)
		     (let* ((handle (hash-create-handle! table obj #t))
			    (first? (cdr handle)))
		       (set-cdr! handle #f)
		       first?))))
      (let rec ((data init)
		(modules (init-thunk)))
	(do ((modules modules (cdr modules))
	     (data data (if (first? (car modules))
			    (rec (fold-module (extract (car modules)) data)
				 (traverse (car modules)))
			    data)))
	    ((null? modules) data))))))

(define (apropos-fold-accessible module)
  (make-fold-modules (lambda () (list module))
		     module-uses
		     identity))

(define (root-modules)
  (submodules (resolve-module '() #f)))

(define (submodules mod)
  (hash-map->list (lambda (k v) v) (module-submodules mod)))

(define apropos-fold-exported
  (make-fold-modules root-modules submodules module-public-interface))

(define apropos-fold-all
  (make-fold-modules root-modules submodules identity))

(define (source obj)
  (cond ((procedure? obj) (procedure-source obj))
	((macro? obj) (procedure-source (macro-transformer obj)))
	(else #f)))

(define (arity obj)
  (define (display-arg-list arg-list)
    (display #\`)
    (display (car arg-list))
    (let loop ((ls (cdr arg-list)))
      (cond ((null? ls)
	     (display #\'))
	    ((not (pair? ls))
	     (display "', the rest in `")
	     (display ls)
	     (display #\'))
	    (else
	     (if (pair? (cdr ls))
		 (display "', `")
		 (display "' and `"))
	     (display (car ls))
	     (loop (cdr ls))))))
  (define (display-arg-list/summary arg-list type)
    (let ((len (length arg-list)))
      (display len)
      (display " ")
      (display type)
      (if (> len 1)
	  (display " arguments: ")
	  (display " argument: "))
      (display-arg-list arg-list)))
  (cond
   ((procedure-property obj 'arglist)
    => (lambda (arglist)
	 (let ((required-args (car arglist))
	       (optional-args (cadr arglist))
	       (keyword-args (caddr arglist))
	       (allow-other-keys? (cadddr arglist))
	       (rest-arg (car (cddddr arglist)))
	       (need-punctuation #f))
	   (cond ((not (null? required-args))
		  (display-arg-list/summary required-args "required")
		  (set! need-punctuation #t)))
	   (cond ((not (null? optional-args))
		  (if need-punctuation (display ", "))
		  (display-arg-list/summary optional-args "optional")
		  (set! need-punctuation #t)))
	   (cond ((not (null? keyword-args))
		  (if need-punctuation (display ", "))
		  (display-arg-list/summary keyword-args "keyword")
		  (set! need-punctuation #t)))
	   (cond (allow-other-keys?
		  (if need-punctuation (display ", "))
		  (display "other keywords allowed")
		  (set! need-punctuation #t)))
	   (cond (rest-arg
		  (if need-punctuation (display ", "))
		  (display "the rest in `")
		  (display rest-arg)
		  (display "'"))))))
   (else
    (let ((arity (procedure-minimum-arity obj)))
      (display (car arity))
      (cond ((caddr arity)
	     (display " or more"))
	    ((not (zero? (cadr arity)))
	     (display " required and ")
	     (display (cadr arity))
	     (display " optional")))
      (if (and (not (caddr arity))
	       (= (car arity) 1)
	       (<= (cadr arity) 1))
	  (display " argument")
	  (display " arguments")))))
  (display ".\n"))


(define (procedure-arguments proc)
  "Return an alist describing the arguments that `proc' accepts, or `#f'
if the information cannot be obtained.

The alist keys that are currently defined are `required', `optional',
`keyword', `allow-other-keys?', and `rest'."
  (cond
   ((procedure-property proc 'arglist)
    => (match-lambda
        ((req opt keyword aok? rest)
         `((required . ,(if (number? req)
                            (make-list req '_)
                            req))
           (optional . ,(if (number? opt)
                            (make-list opt '_)
                            opt))
           (keyword . ,keyword)
           (allow-other-keys? . ,aok?)
           (rest . ,rest)))))
   ((procedure-source proc)
    => cadr)
   (((@ (system vm program) program?) proc)
    ((@ (system vm program) program-arguments-alist) proc))
   (else #f)))


;;; session.scm ends here
