;; - auto-generate docstrings for cl-defstruct slot accessors instead of
;; storing them in the accessor itself?
+;; Related constructs:
+;; - `funcallable-standard-object' (FSO) in Common-Lisp. These are different
+;; from FCRs in that they involve an additional indirection to get
+;; to the actual code, and that they offer the possibility of
+;; changing (via mutation) the code associated with
+;; an FSO. Also the FSO's function can't directly access the FSO's
+;; other fields, contrary to the case with FCRs where those are directly
+;; available as local variables.
+;; - Function objects in Javascript.
+;; - Function objects in Python.
+;; - Callable/Applicable classes in OO languages, i.e. classes with
+;; a single method called `apply' or `call'. The most obvious
+;; difference with FCRs (beside the fact that Callable can be
+;; extended with additional methods) is that all instances of
+;; a given Callable class have to use the same method, whereas every
+;; FCR object comes with its own code, so two FCR objects of the
+;; same type can have different code. Of course, you can get the
+;; same result by turning every `fcr-lambda' into its own class
+;; declaration creating an ad-hoc subclass of the specified type.
+;; In this sense, FCRs are just a generalization of `lambda' which brings
+;; some of the extra feature of Callable objects.
+;; - Apply hooks and "entities" in MIT Scheme
+;; https://www.gnu.org/software/mit-scheme/documentation/stable/mit-scheme-ref/Application-Hooks.html
+;; Apply hooks are basically the same as Common-Lisp's FSOs, and "entities"
+;; are a variant of it where the inner function gets the FSO itself as
+;; additional argument (a kind of "self" arg), thus making it easier
+;; for the code to get data from the object's extra info, tho still
+;; not as easy as with FCRs.
+
;;; Code:
;; Slots are currently immutable, tho they can be updated functionally
;; to perform store-conversion on the variable, so we'd either have
;; to prevent cconv from doing it (which might require a new bytecode op
;; to update the in-closure variable), or we'd have to keep track of which
-;; slots have been store-converted so `fcr-get' can access their value
+;; slots have been store-converted so `fcr--get' can access their value
;; correctly.
;; - If the mutated variable/slot is captured by another (nested) closure
;; store-conversion is indispensable, so if we want to avoid store-conversion
(memq 'fcr-object (fcr--class-allparents (cl--find-class type))))))
(cl-deftype fcr-object () '(satisfies fcr--object-p))
-(defun fcr--defstruct-make-copiers (copiers slots name)
- (require 'cl-macs) ;`cl--arglist-args' is not autoloaded.
- (mapcar
- (lambda (copier)
- (pcase-let*
- ((cname (pop copier))
- (args (or (pop copier) `(&key ,@slots)))
- (doc (or (pop copier)
- (format "Copier for objects of type `%s'." name)))
- (obj (make-symbol "obj"))
- (absent (make-symbol "absent"))
- (anames (cl--arglist-args args))
- (index -1)
- (argvals
- (mapcar
- (lambda (slot)
- (setq index (1+ index))
- (when (memq slot anames)
- ;; FIXME: Skip the `unless' test for mandatory args.
- `(if (eq ',absent ,slot)
- (fcr-get ,obj ,index)
- ,slot)))
- slots)))
- `(cl-defsubst ,cname (&cl-defs (',absent) ,obj ,@args)
- ,doc
- (declare (side-effect-free t))
- (fcr--copy ,obj ,@argvals))))
- copiers))
+(defun fcr--defstruct-make-copiers (copiers slotdescs name)
+ (require 'cl-macs) ;`cl--arglist-args' is not autoloaded.
+ (let* ((mutables '())
+ (slots (mapcar
+ (lambda (desc)
+ (let ((name (cl--slot-descriptor-name desc)))
+ (unless (alist-get :read-only
+ (cl--slot-descriptor-props desc))
+ (push name mutables))
+ name))
+ slotdescs)))
+ (mapcar
+ (lambda (copier)
+ (pcase-let*
+ ((cname (pop copier))
+ (args (or (pop copier) `(&key ,@slots)))
+ (doc (or (pop copier)
+ (format "Copier for objects of type `%s'." name)))
+ (obj (make-symbol "obj"))
+ (absent (make-symbol "absent"))
+ (anames (cl--arglist-args args))
+ (mnames
+ (let ((res '())
+ (tmp args))
+ (while (and tmp
+ (not (memq (car tmp)
+ cl--lambda-list-keywords)))
+ (push (pop tmp) res))
+ res))
+ (index -1)
+ (mutlist '())
+ (argvals
+ (mapcar
+ (lambda (slot)
+ (setq index (1+ index))
+ (let* ((mutable (memq slot mutables))
+ (get `(fcr--get ,obj ,index ,(not (not mutable)))))
+ (push mutable mutlist)
+ (cond
+ ((not (memq slot anames)) get)
+ ((memq slot mnames) slot)
+ (t
+ `(if (eq ',absent ,slot)
+ ,get
+ ,slot)))))
+ slots)))
+ `(cl-defun ,cname (&cl-defs (',absent) ,obj ,@args)
+ ,doc
+ (declare (side-effect-free t))
+ (fcr--copy ,obj ',(if (remq nil mutlist) (nreverse mutlist))
+ ,@argvals))))
+ copiers)))
(defmacro fcr-defstruct (name &optional docstring &rest slots)
(declare (doc-string 2) (indent 1))
(cons sa (merge (cdr slots-a) (cdr slots-b))))))))
class))
parent-names))
- (slotdescs (append
- parent-slots
- (mapcar (lambda (field)
- (cl--make-slot-descriptor field nil nil
- '((:read-only . t))))
- slots)))
+ (slotdescs
+ (append
+ parent-slots
+ (mapcar (lambda (field)
+ (if (not (consp field))
+ (cl--make-slot-descriptor field nil nil
+ '((:read-only . t)))
+ (let ((name (pop field))
+ (type nil)
+ (read-only t)
+ (props '()))
+ (while field
+ (pcase (pop field)
+ (:mutable (setq read-only (not (car field))))
+ (:type (setq type (car field)))
+ (p (message "Unknown property: %S" p)
+ (push (cons p (car field)) props)))
+ (setq field (cdr field)))
+ (cl--make-slot-descriptor name nil type
+ `((:read-only . ,read-only)
+ ,@props)))))
+ slots)))
(allparents (apply #'append (mapcar #'cl--class-allparents
parents)))
(class (fcr--class-make name docstring slotdescs parents
(cl--find-class type))))))))
,@(let ((i -1))
(mapcar (lambda (desc)
- (let ((slot (cl--slot-descriptor-name desc)))
+ (let* ((slot (cl--slot-descriptor-name desc))
+ (mutable
+ (not (alist-get :read-only
+ (cl--slot-descriptor-props desc))))
+ ;; Always use a double hyphen: if users wants to
+ ;; make it public, they can do so with an alias.
+ (name (intern (format "%S--%S" name slot))))
(cl-incf i)
(when (gethash slot it)
(error "Duplicate slot name: %S" slot))
(setf (gethash slot it) i)
- ;; Always use a double hyphen: if users wants to
- ;; make it public, they can do so with an alias.
- `(defalias ',(intern (format "%S--%S" name slot))
- ;; We use `fcr--copy' instead of `fcr--accessor-copy'
- ;; here to circumvent bootstrapping problems.
- (fcr--copy fcr--accessor-prototype
- ',name ',slot ,i))))
+ (if (not mutable)
+ `(defalias ',name
+ ;; We use `fcr--copy' instead of
+ ;; `fcr--accessor-copy' here to circumvent
+ ;; bootstrapping problems.
+ (fcr--copy fcr--accessor-prototype nil
+ ',name ',slot ,i))
+ `(progn
+ (defalias ',name
+ (fcr--accessor-copy
+ fcr--mut-getter-prototype
+ ',name ',slot ,i))
+ (defalias ',(gv-setter name)
+ (fcr--accessor-copy
+ fcr--mut-setter-prototype
+ ',name ',slot ,i))))))
slotdescs))
,@(fcr--defstruct-make-copiers
- copiers (mapcar #'cl--slot-descriptor-name slotdescs) name))))
+ copiers slotdescs name))))
(defun fcr--define (class pred)
(let* ((name (cl--class-name class))
(defalias predname pred)
(put name 'cl-deftype-satisfies predname)))
-(defmacro fcr--lambda (type bindings args &rest body)
+(defmacro fcr--lambda (type bindings mutables args &rest body)
"Low level construction of an FCR object.
TYPE is expected to be a symbol that is (or will be) defined as an FCR type.
BINDINGS should list all the slots expected by this type, in the proper order.
+MUTABLE is a list of symbols indicating which of the BINDINGS
+should be mutable.
No checking is performed,"
(declare (indent 3) (debug (sexp (&rest (sexp form)) sexp def-body)))
;; FIXME: Fundamentally `fcr-lambda' should be a special form.
;; FIXME: Since we use the docstring internally to store the
;; type we can't handle actual docstrings. We could fix this by adding
;; a docstring slot to FCRs.
- ((`(,prebody . ,body) (macroexp-parse-body body)))
+ ((`(,prebody . ,body) (macroexp-parse-body body))
+ (rovars (mapcar #'car bindings)))
+ (dolist (mutable mutables)
+ (setq rovars (delq mutable rovars)))
`(let ,(mapcar (lambda (bind)
(if (cdr bind) bind
;; Bind to something that doesn't look
;; This `fcr--fix-type' + `ignore' call is used by the compiler (in
;; `cconv.el') to detect and signal an error in case of
;; store-conversion (i.e. if a variable/slot is mutated).
- (ignore ,@(mapcar #'car bindings))
+ (ignore ,@rovars)
(lambda ,args
(:documentation ',type)
,@prebody
;; Add dummy code which accesses the field's vars to make sure
;; they're captured in the closure.
- (if t nil ,@(mapcar #'car bindings))
+ (if t nil ,@rovars ,@(mapcar (lambda (m) `(setq ,m ,m)) mutables))
,@body)))))
(defmacro fcr-lambda (type-and-slots args &rest body)
((`(,type . ,fields) type-and-slots)
(class (cl--find-class type))
(slots (fcr--class-slots class))
+ (mutables '())
(slotbinds (mapcar (lambda (slot)
- (list (cl--slot-descriptor-name slot)))
+ (let ((name (cl--slot-descriptor-name slot))
+ (props (cl--slot-descriptor-props slot)))
+ (unless (alist-get :read-only props)
+ (push name mutables))
+ (list name)))
slots))
(tempbinds (mapcar
(lambda (field)
fields)))
;; FIXME: Optimize temps away when they're provided in the right order?
`(let ,tempbinds
- (fcr--lambda ,type ,slotbinds ,args ,@body))))
+ (fcr--lambda ,type ,slotbinds ,mutables ,args ,@body))))
(defun fcr--fix-type (_ignore fcr)
(if (byte-code-function-p fcr)
(cadr fcr))
fcr)))
-(defun fcr--copy (fcr &rest args)
+(defun fcr--copy (fcr mutlist &rest args)
(if (byte-code-function-p fcr)
- (apply #'make-closure fcr args)
+ (apply #'make-closure fcr
+ (if (null mutlist)
+ args
+ (mapcar (lambda (arg) (if (pop mutlist) (list arg) arg)) args)))
(cl-assert (eq 'closure (car-safe fcr)))
(cl-assert (eq :type (caar (cadr fcr))))
(let ((env (cadr fcr)))
,@(nthcdr (1+ (length args)) env))
,@(nthcdr 2 fcr)))))
-(defun fcr-get (fcr index)
+(defun fcr--get (fcr index mutable)
(if (byte-code-function-p fcr)
- (let ((csts (aref fcr 2)))
- (aref csts index))
+ (let* ((csts (aref fcr 2))
+ (v (aref csts index)))
+ (if mutable (car v) v))
(cl-assert (eq 'closure (car-safe fcr)))
(cl-assert (eq :type (caar (cadr fcr))))
(cdr (nth (1+ index) (cadr fcr)))))
+(defun fcr--set (v fcr index)
+ (if (byte-code-function-p fcr)
+ (let* ((csts (aref fcr 2))
+ (cell (aref csts index)))
+ (setcar cell v))
+ (cl-assert (eq 'closure (car-safe fcr)))
+ (cl-assert (eq :type (caar (cadr fcr))))
+ (setcdr (nth (1+ index) (cadr fcr)) v)))
+
(defun fcr-type (fcr)
"Return the type of FCR, or nil if the arg is not a FunCallableRecord."
(if (byte-code-function-p fcr)
;; Use `fcr--lambda' to circumvent a bootstrapping problem:
;; `fcr-accessor' is not yet defined at this point but
;; `fcr--accessor-prototype' is needed when defining `fcr-accessor'.
- (fcr--lambda fcr-accessor ((type) (slot) (index)) (fcr) (fcr-get fcr index)))
+ (fcr--lambda fcr-accessor ((type) (slot) (index)) nil
+ (fcr) (fcr--get fcr index nil)))
(fcr-defstruct accessor
"FCR function to access a specific slot of an object."
"FCR function to access a specific slot of an FCR function."
index)
+(defconst fcr--mut-getter-prototype
+ (fcr-lambda (fcr-accessor (type) (slot) (index)) (fcr)
+ (fcr--get fcr index t)))
+(defconst fcr--mut-setter-prototype
+ ;; FIXME: The generated docstring is wrong.
+ (fcr-lambda (fcr-accessor (type) (slot) (index)) (val fcr)
+ (fcr--set val fcr index)))
+
(provide 'fcr)
;;; fcr.el ends here
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