A little lisp program i got to write should do the following (copied from my old question: LISP - Program to search a specific function through its parameters):
The program should work in 2 different ways:
You give the program the name of a function and it should return the function parameters.
You enter function parameters and if a function with these parameters exists, it should return the name of the function.
I got the following code:
(defun get-name-by-params (database params)
(let ((matching-entries (remove-if-not (lambda (entry)
(equal (second entry) params))
database)))
(mapcar #'first matching-entries)))
(defun get-params-by-name (database function)
(let ((matching-entries (remove-if-not (lambda (entry)
(equal (first entry) function))
database)))
(flatten(mapcar #'second matching-entries))))
(defun flatten (L)
(if (null L)
nil
(if (atom (first L))
(cons (first L) (flatten (rest L)))
(append (flatten (first L)) (flatten (rest L))))))
With that code i get the following results:
(get-params-by-name '((cons (t t) cons) (list (&rest t) list) (append (&rest lists) result)) 'append)
->(&REST LISTS)
(get-name-by-params '((cons (t t) cons) (list (&rest t) list)) '(&rest t))
->(LIST)
That is in both cases exactly what i need. My last problem with my task is that i need to create a database in which the functions and parameters are stored because i will need to add many more functions to the program.
So i need to create a database which stores the following data
'((cons (t t) cons) (list (&rest t) list) (append (&rest lists) result))
and, if possible, can be processed by the given functions.
Could anybody please give me an example how to create a database for this task?
For experimental and quick projects, I tend to use a simple text file that just stores the s-expression.
A very simple database:
(format open-file-stream "~S" any-sexp)
You can look up an entry using some simple functions.
To look up by (implicit) index:
(defun read-nth-sexp (n file)
(with-open-file
(file-stream file)
(loop for i from 0
for sexp = (read file-stream nil)
do (if (eq n i) (return sexp)))))
To find by key:
(Note: You store the key by just adding it to the sexp anywhere in the structure of the sexp, when you stored it. Later you can get at it by providing the relevant selector function, by default assumed to be #'car.)
(defun find-entry (entry file &key (select #'car))
(with-open-file
(file-stream file)
(loop for sexp = (read file-stream nil)
while sexp
do (if (equal (funcall select sexp) entry)
(return sexp)))))
This works well for upto 10,000's or maybe 100'000s of entries, depending on your hardware. I've had difficulty dealing with anything above half million entries.
I haven't had the need to update my data, and so I never wrote any updation functions but they can be written easily.
For very fast search, I've had success with binary search assuming of course your data has sortable properties.
You could design a database in Lisp vs. using a persistent storage database, and you could save the data in a serialized format in order to load/save the database. You'd be surprised, but some big companies such as Yahoo! did this in the 90's, and many still do it today, vs. using a persistent database such as MySQL. Here is an example of the structure of the program if you want to write the database in Lisp. You could use the CLOS to store functions as instances of that class. You say that you need the function name, and the function parameters. So you could create a class with the attributes "name" and "parameters". Here is an example:
(defclass functions()
((name :accessor func-name
:initarg :name)
(params :accessor func-params
:initarg :params
:initform '(nil))))
We can create a class with slots for the name and parameters as I showed above, and then we can create instances of that class. So if for example I have a function like this:
(defun foo (n lst)
(list foo))
I can should create an instance like this...
(defvar func-1 (make-instance 'functions
:name "foo"
:params '("n" "lst")))
And if I have a function like this:
(defun foo-2(lst n)
(list lst n))
I can create another instance like this:
(defvar func-2 (make-instance 'functions
:name "foo-2"
:params '("lst" "n")))
Now how do we store these instances in a database? We have a few options, but a simple and general example would be to store the instances in a list. We could increase the complexity, or even create our own form of an embedded SQL language using Macros, but to keep it simple, we can just use a list and the find function in order to create a make-shift database. Here is an example of a database and two functions to search that database based on a functions name or parameters:
(defvar *func-db* nil) ;Create an empty list to store the functions
(push func-1 *func-db*)
(push func-2 *func-db*) ;Push a couple of functions to the DB
(defun find-params (name)
(func-params
(find name *func-db*
:test #'string-equal
:key #'func-name)))
(defun find-name (param-list)
(func-name
(find param-list *func-db*
:test #'equal
:key #'func-params))
Now we can create a couple of functions to find the params of a function based on the name we search, or find the name of a function based on the params we enter. I will use Strings in this scenario for a simple illustration, but you should probably use symbols. Here are a couple of examples of how we would search the DB:
CL-USER> (find-params "foo")
("n" "lst")
CL-USER> (find-params "foo-2")
("lst" "n")
CL-USER> (find-name '("n" "lst"))
"foo"
CL-USER> (find-name '("lst" "n"))
"foo-2"
That is how we can make a make-shift database in Lisp. A good book to read would be "Practical Common Lisp". There's a free online version, and in that book, one of the main projects is creating an MP3 database. The most simple example is using a List to store information and then searching it. If you want to save the database for later usage, you can save it to a file, and then load it when you want to use it again. This technique might seem simple, but I've seen big companies use it vs. MySQL. You can even create your own embedded SQL language to search for the information, and since the information is stored in memory it could retrieve results even faster than MySQL if you decided to extend this project and create a web application in Lisp.
Related
Is there any standard way in Common Lisp (+common libraries today) how to put default settings for not-yet-loaded libraries/systems (that are from public sources and cannot be reasonably modified) in the config file such as .sbclrc?
For example, I want to have set
(setf quickproject:*template-directory* "~/projects/template/"
quickproject:*author* "my name <etcetc>")
when Quickproject is loaded. (Obviously, there is an additional complication with the relevant package not being defined at that point of time, but this I can handle.)
Something along the lines of emacs's (with)-eval-after-load.
I am interested primarily in sbcl and quicklisp/asdf libraries, but implementation independent solution is preferred.
I tried to find in existing libraries and out of the box functionalities of SBCL require and of asdf, without success.
I considered and rejected abusing sbcl's extensions on trace.
The best I was able to do so far is define method for asdf:operate, something like (for illustration, not really used)
(defvar *after-system-hooks* (make-hash-table :test 'equal))
(defmethod asdf:operate :after ((op asdf:load-op) (component asdf:system) &key)
(let* ((name (asdf:component-name component)))
(dolist (hook (gethash name *after-system-hooks*))
(funcall hook))
(setf (gethash name *after-system-hooks*) nil)))
(defun intern-uninterned (code package)
(typecase code
(cons (cons (intern-uninterned (car code) package)
(intern-uninterned (cdr code) package)))
(symbol (if (symbol-package code) code (intern (symbol-name code) package)))
(t code)))
(defmacro with-eval-after-load ((name package) &body body)
`(let ((fn (lambda () (eval (intern-uninterned '(progn ,#body) ',package)))))
(if (member ,name (asdf:already-loaded-systems) :test 'equal)
(funcall fn)
(push fn (gethash ,name *after-system-hooks*)))))
and then write something like
(with-eval-after-load ("quickproject" :quickproject)
(setf
#:*template-directory* "~/projects/template/"
#:*author* "My Name <etcetc>"))
However, this is overwriting method on standard component dispatched on standard classes, so it does not seem safe and future-proof. And I do not see how to define new classes to specialize in such a way that it would work with existing systems and tooling.
(And it has eval, but it does not bother me much here)
You are on the right track with asdf:operate. But instead of specializing on asdf:system in general, use EQL Specializer:
(defmethod asdf:operate :after ((op asdf:load-op) (component (eql (asdf:find-system "quickproject"))) &key)
... )
This method only gets called after loading Quickproject.
I would also get rid of extra abstractions and just do want I want to do in the method itself. There is uiop:symbol-call to call a function which isn't loaded yet. But I wouldn't mind using eval with a fixed string.
To use this method (and similar custom forms) from multiple implementations, just put this in a shared-init.lisp file and then load this file in each implementation's init file.
As for common libraries for settings and configs for your own code, I have used https://github.com/Shinmera/ubiquitous before, which worked without any issues.
In my program I have constant strings, the values are known at compilation time. For each offset there are currently 2 associated strings. I first wrote the following code:
(eval-when (:compile-toplevel :load-toplevel :execute) ;; BLOCK-1
(defstruct test-struct
str-1
str-2))
(eval-when (:compile-toplevel) ;; BLOCK-2
(defparameter +GLOBAL-VECTOR-CONSTANT+ nil) ;; ITEM-1
(let ((vector (make-array 10
:initial-element (make-test-struct)
:element-type 'test-struct)))
(setf (test-struct-str-1 (aref vector 0)) "test-0-1")
(setf (test-struct-str-2 (aref vector 0)) "test-0-2")
(setf +GLOBAL-VECTOR-CONSTANT+ vector)))
(format t "[~A]~%" (test-struct-str-1 (elt +GLOBAL-VECTOR-CONSTANT+ 0)))
(format t "[~A]~%" (test-struct-str-2 (elt +GLOBAL-VECTOR-CONSTANT+ 0)))
This seems to work as it returns the following:
[test-2-1]
[test-2-2]
In BLOCK-1 the struct containing the data is defined, for compile-time, load-time and execute-time. In BLOCK-2, the code which create a vector and sets the values is executed, at compile-time.
But I have the following concerns:
This code seems unnecessary verbose
The strings are stored in a structure
I need to manually set the offset of each values ((aref vector 0), (aref vector 1), etc).
When I set ITEM-1 inside BLOCK-1 instead of BLOCK-2 I get an error in SBCL which I don't understand
What is the idiomatic way to define complex constants in Common Lisp?
It's not really clear what you want to do from your question.
First important note: your code is seriously broken. It's broken because you define +global-vector-constant+ only at compile time but refer to it later than that. If you compile this file and then load that compiled file into a cold image you will get errors.
It is absolutely critical when dealing with things like this to make sure that your code will compile in a cold Lisp. One of the classic problems with resident environments (which CL isn't really, compared to the way Interlisp-D was for instance) is to end up with systems which you can't cold build: I'm pretty sure I worked for several years with an Interlisp-D sysout that no-one knew how to cold build any more.
If what you want is an object (an array, for instance) whose initial value is computed at compile time and then treated as a literal, then the answer to that is, in general, a macro: macros are exactly functions which do their work at compile time, and so a macro can expand to a literal. In addition it must be the case that the object you want to be a literal is externalizable (which means 'can be dumped in compiled files') and anything involved in it is known about at compile time. Instances of some classes are externalizable by default, those of some other classes can be made externalizable by user code, and some are not externalizable at all (for instance functions).
In quite a lot of simple cases, like the one you gave, if I understand it, you don't really need a macro, and in fact you can almost always get away without one, although it may make your code easier to understand if you do use one.
Here is a simple case: many arrays are externalizable if their elements are
(defparameter *my-strings*
#(("0-l" . "0-r")
("1-l" . "1-r")))
This means that *my-strings* will be bound to a literal array of conses of strings.
A more interesting case is when the elements are, for instance structures. Well, structures are also externalizable, so we can do that. And in fact it's quite possible, still, to avoid a macro, although it now becomes a bit noisy.
(eval-when (:compile-toplevel :load-toplevel :execute)
(defstruct foo
l
r))
(defparameter *my-strings*
#(#s(foo :l "0-l" :r "0-r")
#s(foo :l "1-l" :r "1-r")))
Note that the following won't work:
(defstruct foo
l
r)
(defparameter *my-strings*
#(#s(foo :l "0-l" :r "0-r")
#s(foo :l "1-l" :r "1-r")))
It won't work because, at compile time, you are trying to externalize instances of a structure which is not yet defined (but it probably will work if the Lisp is not cold, and you might even be able to reload the compiled file you made that way). Again, in this case you can avoid the eval-when in a larger system by ensuring that the file which defines the foo structure is compiled and loaded before the file with the defparameter is loaded.
And even in more complex cases you can escape using a macro. For instance for many sorts of objects which are normally not externalizable you can teach the system how to externalize them, and then splice the object in as a literal using #.:
(eval-when (:compile-toplevel :load-toplevel :execute)
;; Again, this would be in its own file in a bigger system
(defclass string-table-wrapper ()
((strings)
(nstrings :initform 0)))
(defmethod initialize-instance :after ((w string-table-wrapper)
&key (strings '()))
(let ((l (length strings)))
(when l
(with-slots ((s strings) (n nstrings)) w
(setf s (make-array l :initial-contents strings)
n l)))))
(defmethod make-load-form ((w string-table-wrapper) &optional environment)
(make-load-form-saving-slots w :slot-names '(strings nstrings)
:environment environment))
) ;eval-when
(defgeneric get-string (from n)
(:method ((from string-table-wrapper) (n fixnum))
(with-slots (strings nstrings) from
(assert (< -1 n nstrings )
(n)
"bad index")
(aref strings n))))
(defparameter *my-strings*
#.(make-instance 'string-table-wrapper
:strings '("foo" "bar")))
Note that, of course, although the value of *my-strings* is a literal, code ran to reconstruct this object at load-time. But that is always the case: it's just that in this case you had to define what code needed to run. Instead of using make-load-form-saving-slots you could have done this yourself, for instance by something like this:
(defmethod make-load-form ((w string-table-wrapper) &optional environment)
(declare (ignore environment))
(if (slot-boundp w 'strings)
(values
`(make-instance ',(class-of w))
`(setf (slot-value ,w 'strings)
',(slot-value w 'strings)
(slot-value ,w 'nstrings)
,(slot-value w 'nstrtrings)))
`(make-instance ',(class-of w))))
But make-load-form-saving-slots is much easier.
Here is an example where a macro does perhaps least make reading the code easier.
Let's assume you have a function which reads an array of strings from a file, for instance this:
(defun file-lines->svector (file)
;; Needs CL-PPCRE
(with-open-file (in file)
(loop
with ltw = (load-time-value
(create-scanner '(:alternation
(:sequence
:start-anchor
(:greedy-repetition 1 nil
:whitespace-char-class))
(:sequence
(:greedy-repetition 1 nil
:whitespace-char-class)
:end-anchor)))
t)
for nlines upfrom 0
for line = (read-line in nil)
while line
collect (regex-replace-all ltw line "") into lines
finally (return (make-array nlines :initial-contents lines)))))
Then, if this function is available at macroexpansion time, you could write this macro:
(defmacro file-strings-literal (file)
(check-type file (or string pathname) "pathname designator")
(file-lines->svector file))
And now we can create a literal vector of strings:
(defparameter *fl* (file-strings-literal "/tmp/x"))
However you could perfectly well instead do this:
(defparameter *fl* #.(file-lines->svector "/tmp/x"))
Which will do the same thing, but slightly earlier (at read time, rather than at macroexpansion/compile time). So this is gaining nothing really.
But you could also do this:
(defmacro define-stringtable (name file &optional (doc nil docp))
`(defparameter ,name ,(file-lines->svector file)
,#(if docp (list doc) nil)))
And now your code reads like
(define-stringtable *st* "my-stringtable.dat")
And that actually is a significant improvement.
Finally note that in file-lines->svector that load-time-value is used to create the scanner exactly once, at load time, which is a related trick.
First of all, your let code can be simplified to
(defparameter +global-vector-constant+
(let ((vector ...))
...
vector))
Second, you can also do
(defparameter +global-vector-constant+
(make-array 10 :element-type 'test-struct :initial-content
(cons (make-test-struct :str-1 "test-0-1" :str-2 "test-0-2")
(loop :repeat 9 :collect (make-test-struct)))))
Note that the benefit of :element-type 'test-struct is generally limited to code self-documentation (see upgraded-array-element-type)
I am learning Common Lisp using Emacs, SBCL and Slime.
I would like to know exactly what is the code definition of the built-in functions.
I know how to use (documentation ...) and (describe ...). However, they provide only high level information. I would like to see the code details.
For instance, take the nth built-in function.
Documentation gives us:
CL-USER> (documentation 'nth 'function)
"Return the nth object in a list where the car is the zero-th element."
Describe gives me:
CL-USER> (describe 'nth)
COMMON-LISP:NTH
[symbol]
NTH names a compiled function:
Lambda-list: (SB-IMPL::N LIST)
Declared type: (FUNCTION (UNSIGNED-BYTE LIST) (VALUES T &OPTIONAL))
Derived type: (FUNCTION (T T) (VALUES T &OPTIONAL))
Documentation:
Return the nth object in a list where the car is the zero-th element.
Inline proclamation: MAYBE-INLINE (inline expansion available)
Known attributes: foldable, flushable, unsafely-flushable
Source file: SYS:SRC;CODE;LIST.LISP
(SETF NTH) names a compiled function:
Lambda-list: (SB-KERNEL::NEWVAL SB-IMPL::N LIST)
Derived type: (FUNCTION (T UNSIGNED-BYTE LIST) (VALUES T &OPTIONAL))
Inline proclamation: INLINE (inline expansion available)
Source file: SYS:SRC;CODE;SETF-FUNS.LISP
(SETF NTH) has a complex setf-expansion:
Lambda-list: (SB-IMPL::N LIST)
(undocumented)
Source file: SYS:SRC;CODE;DEFSETFS.LISP
; No value
I would like to see something like:
(unknown-command 'nth)
Which would return something like:
(defun nth (x xs)
(if (equal x 0)
(car xs)
(my-nth (- x 1) (cdr xs))))
Lisp languages are fantastic and have a huge ecossystem built by awesome programmers. I hope there is some tool or command for that.
Thanks
First, some general clarifications
In your own code, hitting Meta-. should take you to the source of the code
This will also "just work" for libraries installed via Quicklisp.
Now for SBCL code itself:
If the code is in the "expected place", hitting Meta-. on built-in functions (like nth in your example above) will also take you to its source. I believe the default is /usr/share/sbcl-source/src/code/ but there's possibly a way to configure it.
However, there's another practical way to view this: if you look at the output of (describe ...) above, the line was:
Source file: SYS:SRC;CODE;LIST.LISP
Note: not the last line, that is for (setf nth), something slightly different
This tells you which file in the SBCL source code you can expect to find the function definition.
So, within [the repo](https:/ /github.com/sbcl/sbcl/tree/master/src), if you locate src/code/list.lisp, you should find the definition you're looking for; reproducing here:
(defun nth (n list)
"Return the nth object in a list where the car is the zero-th element."
(declare (explicit-check)
(optimize speed))
(typecase n
((and fixnum unsigned-byte)
(block nil
(let ((i n)
(result list))
(tagbody
loop
(the list result)
(if (plusp i)
(psetq i (1- i)
result (cdr result))
(return (car result)))
(go loop)))))
(t
(car (nthcdr n list)))))
When such information is available, it should be accessible via function-lambda-expression :
* (FUNCTION-LAMBDA-EXPRESSION #'nth)
(LAMBDA (SB-IMPL::N LIST)
(DECLARE (SB-INT:EXPLICIT-CHECK)
(OPTIMIZE SPEED))
(BLOCK NTH
(TYPECASE SB-IMPL::N
((AND FIXNUM UNSIGNED-BYTE)
(BLOCK NIL
(LET ((SB-IMPL::I SB-IMPL::N) (SB-IMPL::RESULT LIST))
(TAGBODY
LOOP
(THE LIST SB-IMPL::RESULT)
(IF (PLUSP SB-IMPL::I)
(PSETQ SB-IMPL::I (1- SB-IMPL::I)
SB-IMPL::RESULT (CDR SB-IMPL::RESULT))
(RETURN (CAR SB-IMPL::RESULT)))
(GO LOOP)))))
(T (CAR (NTHCDR SB-IMPL::N LIST))))))
NIL
NTH
However, it is not always available, in which case you would have to go to the SBCL source code repository.
Can someone explain why I get different results for the following simple program with sbcl and clisp? Is what I am doing undefined by the language, or is one of the two lisp interpreters wrong?
; Modify the car of the passed-in list
(defun modify (a) (setf (car a) 123))
; Create a list and print car before and after calling modify
(defun testit () (let ((a '(0)))
(print (car a))
(modify a)
(print (car a))))
(testit)
SBCL (version 1.0.51) produces:
0
0
CLISP (version 2.49) produces (what I would expect):
0
123
I agree with Seth's and Vsevolod's comments in that this behavior is due to your modification of literal data. Try using (list 0) instead of '(0). Questions relating to this come up relatively frequently, so I'll quote the HyperSpec here.
3.7.1 Modification of Literal Objects:
The consequences are undefined if literal objects are destructively
modified.
The definition of "literal":
literal adj. (of an object) referenced directly in a program rather
than being computed by the program; that is, appearing as data in a
quote form, or, if the object is a self-evaluating object, appearing
as unquoted data. ``In the form (cons "one" '("two")), the expressions
"one", ("two"), and "two" are literal objects.''
Note that often (in many implementations), if you modify literal values, you'll really modify them in the code itself – writing self modifying code. Your example code will not work as you expect.
Your example code in CCL:
CL-USER> (defun modify (a) (setf (car a) 123))
MODIFY
CL-USER> (defun testit ()
(let ((a '(0)))
(print (car a))
(modify a)
(print (car a))))
TESTIT
CL-USER> (testit)
0
123
123
CL-USER> (testit)
123
123
123
Take a look at the second evaluation of testit, where the let itself really already contains the modified value, thus the first print also yields 123.
Also see: Lisp, cons and (number . number) difference, where I explained this in more detail, or the question linked in Vsevolod's comment above.
Isn't it possible to treat functions in Scheme as any other list?
Basically, what I want do to is something like this:
(define (foo) "hello")
(cdr foo) ; or similar, should return the list ((foo) "hello")
I've found a similar discussion about this, and I feel a bit disappointed if this is not possible with Scheme. If so, why is this impossible? Is it possible in other lisps?
EDIT: Changed (cdr 'foo) to (cdr foo) -- it was misleading. I'm asking, why can't I access a function as a list?
I have often wanted to be able to do the same thing csl.
Below is a quick example of how you could go about doing this in mzscheme.
DrScheme 4.2
(module qdefine mzscheme
(provide ;(all-from-except mzscheme let)
(rename define olddefine)
(rename quote-define define)
(rename quote-cdr cdr)
(rename quote-car car))
(define define-list '())
(define define-list-add
(lambda (key value)
(set! define-list (cons `(,key ,value) define-list))))
(define-syntax quote-define
(syntax-rules ()
((_ (pro-name args ...) body ...)
(begin
(define (pro-name args ...) body ...)
(define-list-add pro-name '((pro-name args ...) body ...))))
((_ pro-name pro) (begin
(define pro-name pro)
(define-list-add pro-name 'pro)))
))
(define quote-cdr (lambda (lst)
(if (procedure? lst)
(cdr (cadr (assoc lst define-list)))
(cdr lst))))
(define quote-car (lambda (lst)
(if (procedure? lst)
(car (cadr (assoc lst define-list)))
(car lst))))
)
(require 'qdefine)
(define testfunc (lambda (args) args))
(cdr testfunc)
(car testfunc)
(define (testfunc2 test) 'blah)
(cdr testfunc2)
(car testfunc2)
(define testlist '(1 2 3 4 5 6 'a))
(cdr testlist)
(car testlist)
Outputs:
((args) args)
lambda
('blah)
(testfunc2 test)
(2 3 4 5 6 'a)
1
>
Your define form is not a function but a function definition. In fact, it is a shorthand for
(define foo
(lambda ()
"hello"))
Lambda can be thought of as a "compiler invocation". In this case, it produces a function which returns that string. Define then binds this function to the symbol 'foo.
Compare this to
(define foo "hello")
which binds just the string to the symbol 'foo. What would (cdr foo) return?
Now, it is imaginable that some Scheme implementation actually saves or has the option to save the lambda form when binding a function to a symbol. You will have to check the documentation, but the kind of pure interpretation this implies surely would have an impact on performance.
If you manage to get this, though, it will return the lambda form, not the define form.
MIT Scheme has the ability to do this. (If you really want, comment on this and I'll give you the code. I had to find some undocumented functions to make it happen.)
However, it's not in the Scheme language definition, so implementations don't have to allow it. The reason for this is that in order to make functions faster, a good Scheme implementation will modify the functions. This means both rewriting them in a different language (either machine code or something fairly low-level) and taking out any bits you don't need - for instance, the + function must in general check whether its arguments are numbers, and if so, what sort of numbers, but if your function is a loop which calls +, you can just check once at the beginning, and make the function a lot faster.
Of course, you could still keep the lists around without too much trouble, even with all of these things. But if you tried to modify the lists, how would it work?
(Again, you could make it work. It would just be more work for implementers, and since it's not usually used in programs, most people probably just don't want to bother.)
In guile,
guile> (define (foo bar) 'baz)
guile> (procedure-source foo)
(lambda (bar) (quote baz))
guile> (cdr (procedure-source foo))
((bar) (quote baz))
guile>
'foo evaluates to a symbol, you can't take the CDR of a symbol.
What you may want to do is (cdr foo), but this does not work. The value of a FOO is a procedure, not a list.
You might be able to access the function as a list using pp or pretty-print. That said, you might also need to run your code in debug mode. This is very implementation dependent however. I know it can work in Gambit-C.
(define (foo) ...) produces a compiled object, and it's a value - a procedure.
You cannot iterate over it because it is not an s-expression.
Like what other suggested, you should check out your programming environment and see
if it has any facilities for such tasks.