1 ;;;# ParenScript Language Reference
3 ;;; This chapters describes the core constructs of ParenScript, as
4 ;;; well as its compilation model. This chapter is aimed to be a
5 ;;; comprehensive reference for ParenScript developers. Programmers
6 ;;; looking for how to tweak the ParenScript compiler itself should
7 ;;; turn to the ParenScript Internals chapter.
9 ;;;# Statements and Expressions
10 ;;;t \index{statement}
11 ;;;t \index{expression}
13 ;;; In contrast to Lisp, where everything is an expression, JavaScript
14 ;;; makes the difference between an expression, which evaluates to a
15 ;;; value, and a statement, which has no value. Examples for
16 ;;; JavaScript statements are `for', `with' and `while'. Most
17 ;;; ParenScript forms are expression, but certain special forms are
18 ;;; not (the forms which are transformed to a JavaScript
19 ;;; statement). All ParenScript expressions are statements
20 ;;; though. Certain forms, like `IF' and `PROGN', generate different
21 ;;; JavaScript constructs whether they are used in an expression
22 ;;; context or a statement context. For example:
24 (+ i
(if 1 2 3)) => i
+ (1 ?
2 : 3)
33 ;;;# Symbol conversion
35 ;;;t \index{symbol conversion}
37 ;;; Lisp symbols are converted to JavaScript symbols by following a
38 ;;; few simple rules. Special characters `!', `?', `#', `@', `%',
39 ;;; '/', `*' and `+' get replaced by their written-out equivalents
40 ;;; "bang", "what", "hash", "at", "percent", "slash",
41 ;;; "start" and "plus" respectively. The `$' character is untouched.
43 !?
#@%
=> bangwhathashatpercent
45 ;;; The `-' is an indication that the following character should be
46 ;;; converted to uppercase. Thus, `-' separated symbols are converted
47 ;;; to camelcase. The `_' character however is left untouched.
49 bla-foo-bar
=> blaFooBar
51 ;;; If you want a JavaScript symbol beginning with an uppercase, you
52 ;;; can either use a leading `-', which can be misleading in a
53 ;;; mathematical context, or a leading `*'.
57 ;;; The `.' character is left as is in symbols. This allows the
58 ;;; ParenScript programmer to use a practical shortcut when accessing
59 ;;; slots or methods of JavaScript objects. Instead of writing
61 (slot-value foobar
'slot
)
67 ;;; A symbol beggining and ending with `+' or `*' is converted to all
68 ;;; uppercase, to signify that this is a constant or a global
71 *global-array
* => GLOBALARRAY
73 *global-array
*.length
=> GLOBALARRAY.length
75 ;;;## Reserved Keywords
77 ;;;t \index{reserved keywords}
79 ;;; The following keywords and symbols are reserved in ParenScript,
80 ;;; and should not be used as variable names.
82 ! ~
++ --
* / %
+ -
<< >> >>> < > <= >= == != ==== !== & ^ |
&& ||
*=
83 /= %
= += -
= <<= >>= >>>= &= ^
= |
= 1-
1+ ABSTRACT AND AREF ARRAY
84 BOOLEAN BREAK BYTE CASE CATCH CC-IF CHAR CLASS COMMA CONST CONTINUE
85 CREATE DEBUGGER DECF DEFAULT DEFUN DEFVAR DELETE DO DOEACH DOLIST
86 DOTIMES DOUBLE ELSE ENUM EQL EXPORT EXTENDS FALSE FINAL FINALLY FLOAT
87 FLOOR FOR FUNCTION GOTO IF IMPLEMENTS IMPORT IN INCF INSTANCEOF INT
88 INTERFACE JS LAMBDA LET
* LEXICAL-LET
* LISP LIST LONG MAKE-ARRAY NATIVE
89 NEW NIL NOT OR PACKAGE PRIVATE PROGN PROTECTED PUBLIC RANDOM REGEX
90 RETURN SETF SHORT SLOT-VALUE STATIC SUPER SWITCH SYMBOL-MACROLET
91 SYNCHRONIZED T THIS THROW THROWS TRANSIENT TRY TYPEOF UNDEFINED UNLESS
92 VAR VOID VOLATILE WHEN WHILE WITH WITH-SLOTS
95 ;;;t \index{literal value}
99 ;;;t \index{number literal}
101 ; number ::= a Lisp number
104 ;;; ParenScript supports the standard JavaScript literal
105 ;;; values. Numbers are compiled into JavaScript numbers.
111 ;;; Note that the base is not conserved between Lisp and JavaScript.
115 ;;;## String literals
117 ;;;t \index{string literal}
119 ; string ::= a Lisp string
121 ;;; Lisp strings are converted into JavaScript literals.
125 "bratzel bub" => 'bratzel bub
'
127 ;;; Escapes in Lisp are not converted to JavaScript escapes. However,
128 ;;; to avoid having to use double backslashes when constructing a
129 ;;; string, you can use the CL-INTERPOL library by Edi Weitz.
134 ;;;t \index{MAKE-ARRAY}
136 ;;;t \index{array literal}
139 ; (MAKE-ARRAY {values}*)
142 ; values ::= a ParenScript expression
143 ; array ::= a ParenScript expression
144 ; index ::= a ParenScript expression
146 ;;; Array literals can be created using the `ARRAY' form.
150 (array 1 2 3) => [ 1, 2, 3 ]
153 (array "foobar" "bratzel bub"))
154 => [ [ 2, 3 ], [ 'foobar
', 'bratzel bub
' ] ]
156 ;;; Arrays can also be created with a call to the `Array' function
157 ;;; using the `MAKE-ARRAY'. The two forms have the exact same semantic
158 ;;; on the JavaScript side.
160 (make-array) => new Array
()
162 (make-array 1 2 3) => new Array
(1, 2, 3)
166 (make-array "foobar" "bratzel bub"))
167 => new Array
(new Array
(2, 3), new Array
('foobar
', 'bratzel bub
'))
169 ;;; Indexing arrays in ParenScript is done using the form `AREF'. Note
170 ;;; that JavaScript knows of no such thing as an array. Subscripting
171 ;;; an array is in fact reading a property from an object. So in a
172 ;;; semantic sense, there is no real difference between `AREF' and
175 ;;;## Object literals
177 ;;;t \index{SLOT-VALUE}
178 ;;;t \index{WITH-SLOTS}
179 ;;;t \index{object literal}
181 ;;;t \index{object property}
182 ;;;t \index{property}
184 ; (CREATE {name value}*)
185 ; (SLOT-VALUE object slot-name)
186 ; (WITH-SLOTS ({slot-name}*) object body)
188 ; name ::= a ParenScript symbol or a Lisp keyword
189 ; value ::= a ParenScript expression
190 ; object ::= a ParenScript object expression
191 ; slot-name ::= a quoted Lisp symbol
192 ; body ::= a list of ParenScript statements
195 ;;; Object literals can be create using the `CREATE' form. Arguments
196 ;;; to the `CREATE' form is a list of property names and values. To be
197 ;;; more "lispy", the property names can be keywords.
199 (create :foo
"bar" :blorg
1)
205 :another-object
(create :schtrunz
1))
208 anotherObject
: { schtrunz
: 1 } }
210 ;;; Object properties can be accessed using the `SLOT-VALUE' form,
211 ;;; which takes an object and a slot-name.
213 (slot-value an-object
'foo
) => anObject.foo
215 ;;; A programmer can also use the "." symbol notation explained above.
217 an-object.foo
=> anObject.foo
219 ;;; The form `WITH-SLOTS' can be used to bind the given slot-name
220 ;;; symbols to a macro that will expand into a `SLOT-VALUE' form at
223 (with-slots (a b c
) this
225 => this.a
+ this.b
+ this.c
;
227 ;;;## Regular Expression literals
229 ;;;t \index{regular expression}
230 ;;;t \index{CL-INTERPOL}
234 ; regex ::= a Lisp string
236 ;;; Regular expressions can be created by using the `REGEX' form. If
237 ;;; the argument does not start with a slash, it is surrounded by
238 ;;; slashes to make it a proper JavaScript regex. If the argument
239 ;;; starts with a slash it is left as it is. This makes it possible
240 ;;; to use modifiers such as slash-i (case-insensitive) or
241 ;;; slash-g (match-globally (all)).
243 (regex "foobar") => /foobar
/
245 (regex "/foobar/i") => /foobar
/i
247 ;;; Here CL-INTERPOL proves really useful.
249 (regex #?r
"/([^\s]+)foobar/i") => /([^\s
]+)foobar
/i
251 ;;;## Literal symbols
255 ;;;t \index{UNDEFINED}
257 ;;;t \index{literal symbols}
261 ; T, FALSE, NIL, UNDEFINED, THIS
263 ;;; The Lisp symbols `T' and `FALSE' are converted to their JavaScript
264 ;;; boolean equivalents `true' and `false'.
270 ;;; The Lisp symbol `NIL' is converted to the JavaScript keyword
275 ;;; The Lisp symbol `UNDEFINED' is converted to the JavaScript keyword
278 UNDEFINED
=> undefined
280 ;;; The Lisp symbol `THIS' is converted to the JavaScript keyword
286 ;;;t \index{variable}
289 ; variable ::= a Lisp symbol
291 ;;; All the other literal Lisp values that are not recognized as
292 ;;; special forms or symbol macros are converted to JavaScript
293 ;;; variables. This extreme freedom is actually quite useful, as it
294 ;;; allows the ParenScript programmer to be flexible, as flexible as
295 ;;; JavaScript itself.
299 a-variable
=> aVariable
303 *math.floor
=> Math.floor
305 ;;;# Function calls and method calls
306 ;;;t \index{function}
307 ;;;t \index{function call}
309 ;;;t \index{method call}
311 ; (function {argument}*)
312 ; (method object {argument}*)
314 ; function ::= a ParenScript expression or a Lisp symbol
315 ; method ::= a Lisp symbol beginning with .
316 ; object ::= a ParenScript expression
317 ; argument ::= a ParenScript expression
319 ;;; Any list passed to the JavaScript that is not recognized as a
320 ;;; macro or a special form (see "Macro Expansion" below) is
321 ;;; interpreted as a function call. The function call is converted to
322 ;;; the normal JavaScript function call representation, with the
323 ;;; arguments given in paren after the function name.
325 (blorg 1 2) => blorg
(1, 2)
327 (foobar (blorg 1 2) (blabla 3 4) (array 2 3 4))
328 => foobar
(blorg(1, 2), blabla
(3, 4), [ 2, 3, 4 ])
330 ((aref foo i
) 1 2) => foo
[i](1, 2)
332 ;;; A method call is a function call where the function name is a
333 ;;; symbol and begins with a "." . In a method call, the name of the
334 ;;; function is append to its first argument, thus reflecting the
335 ;;; method call syntax of JavaScript. Please note that most method
336 ;;; calls can be abbreviated using the "." trick in symbol names (see
337 ;;; "Symbol Conversion" above).
339 (.blorg this 1 2) => this.blorg(1, 2)
341 (this.blorg 1 2) => this.blorg(1, 2)
343 (.blorg (aref foobar 1) NIL T)
344 => foobar[1].blorg(null, true)
346 ;;;# Operator Expressions
347 ;;;t \index{operator}
348 ;;;t \index{operator expression}
349 ;;;t \index{assignment operator}
355 ; (operator {argument}*)
356 ; (single-operator argument)
358 ; operator ::= one of *, /, %, +, -, <<, >>, >>>, < >, EQL,
359 ; ==, !=, =, ===, !==, &, ^, |, &&, AND, ||, OR.
360 ; single-operator ::= one of INCF, DECF, ++, --, NOT, !
361 ; argument ::= a ParenScript expression
363 ;;; Operator forms are similar to function call forms, but have an
364 ;;; operator as function name.
366 ;;; Please note that `=' is converted to `==' in JavaScript. The `='
367 ;;; ParenScript operator is not the assignment operator. Unlike
368 ;;; JavaScript, ParenScript supports multiple arguments to the
377 ;;; Note that the resulting expression is correctly parenthesized,
378 ;;; according to the JavaScript operator precedence that can be found
379 ;;; in table form at:
381 http://www.codehouse.com/javascript/precedence/
383 (* 1 (+ 2 3 4) 4 (/ 6 7))
384 => 1 * (2 + 3 + 4) * 4 * (6 / 7)
386 ;;; The pre increment and decrement operators are also
387 ;;; available. `INCF' and `DECF' are the pre-incrementing and
388 ;;; pre-decrementing operators. These operators can
389 ;;; take only one argument.
395 ;;; The `1+' and `1-' operators are shortforms for adding and
402 ;;; The `not' operator actually optimizes the code a bit. If `not' is
403 ;;; used on another boolean-returning operator, the operator is
406 (not (< i 2)) => i >= 2
408 (not (eql i 2)) => i != 2
411 ;;;t \index{body form}
413 ;;;t \index{body statement}
415 ; (PROGN {statement}*) in statement context
416 ; (PROGN {expression}*) in expression context
418 ; statement ::= a ParenScript statement
419 ; expression ::= a ParenScript expression
421 ;;; The `PROGN' special form defines a sequence of statements when
422 ;;; used in a statement context, or sequence of expression when used
423 ;;; in an expression context. The `PROGN' special form is added
424 ;;; implicitly around the branches of conditional executions forms,
425 ;;; function declarations and iteration constructs.
427 ;;; For example, in a statement context:
429 (progn (blorg i) (blafoo i))
433 ;;; In an expression context:
435 (+ i (progn (blorg i) (blafoo i)))
436 => i + (blorg(i), blafoo(i))
438 ;;; A `PROGN' form doesn't lead to additional indentation or
439 ;;; additional braces around it's body.
441 ;;;# Function Definition
442 ;;;t \index{function}
444 ;;;t \index{function definition}
448 ;;;t \index{anonymous function}
450 ; (DEFUN name ({argument}*) body)
451 ; (LAMBDA ({argument}*) body)
453 ; name ::= a Lisp Symbol
454 ; argument ::= a Lisp symbol
455 ; body ::= a list of ParenScript statements
457 ;;; As in Lisp, functions are defined using the `DEFUN' form, which
458 ;;; takes a name, a list of arguments, and a function body. An
459 ;;; implicit `PROGN' is added around the body statements.
461 (defun a-function (a b)
463 => function aFunction(a, b) {
467 ;;; Anonymous functions can be created using the `LAMBDA' form, which
468 ;;; is the same as `DEFUN', but without function name. In fact,
469 ;;; `LAMBDA' creates a `DEFUN' with an empty function name.
471 (lambda (a b) (return (+ a b)))
477 ;;;t \index{assignment}
480 ;;;t \index{assignment operator}
484 ; lhs ::= a ParenScript left hand side expression
485 ; rhs ::= a ParenScript expression
487 ;;; Assignment is done using the `SETF' form, which is transformed
488 ;;; into a series of assignments using the JavaScript `=' operator.
492 (setf a 2 b 3 c 4 x (+ a b c))
498 ;;; The `SETF' form can transform assignments of a variable with an
499 ;;; operator expression using this variable into a more "efficient"
500 ;;; assignment operator form. For example:
502 (setf a (1+ a)) => a++;
504 (setf a (+ a 2 3 4 a)) => a += 2 + 3 + 4 + a;
506 (setf a (- 1 a)) => a = 1 - a;
508 ;;; New types of setf places can be defined in one of two ways: using
509 ;;; `DEFSETF' or using `DEFUN' with a setf function name; both are
510 ;;; analogous to their Common Lisp counterparts.
512 ;;; `DEFSETF' supports both long and short forms, while `DEFUN' of a
513 ;;; setf place generates a JavaScript function name with the __setf_
516 (defun (setf color) (new-color el)
517 (setf (slot-value (slot-value el 'style) 'color) new-color))
518 => function __setf_color(newColor, el) {
519 el.style.color = newColor;
522 (setf (color some-div) (+ 23 "em"))
523 => var _js2 = someDiv;
524 var _js1 = 23 + 'em';
525 __setf_color(_js1, _js2);
528 ;;; Note that temporary variables are generated to preserve evaluation
529 ;;; order of the arguments as they would be in Lisp.
531 ;;; The following example illustrates how setf places can be used to
532 ;;; provide a uniform protocol for positioning elements in HTML pages:
534 (defsetf left (el) (offset)
535 `(setf (slot-value (slot-value ,el 'style) 'left) ,offset)) => null
537 (setf (left some-div) (+ 123 "px"))
538 => var _js2 = someDiv;
539 var _js1 = 123 + 'px';
540 _js2.style.left = _js1;
542 (progn (defmacro left (el)
543 `(slot-value ,el 'offset-left))
545 => someDiv.offsetLeft;
547 ;;;# Single argument statements
548 ;;;t \index{single-argument statement}
552 ;;;t \index{function}
557 ; value ::= a ParenScript expression
559 ;;; The single argument statements `return' and `throw' are generated
560 ;;; by the form `RETURN' and `THROW'. `THROW' has to be used inside a
561 ;;; `TRY' form. `RETURN' is used to return a value from a function
564 (return 1) => return 1
566 (throw "foobar") => throw 'foobar'
568 ;;;# Single argument expression
569 ;;;t \index{single-argument expression}
570 ;;;t \index{object creation}
571 ;;;t \index{object deletion}
575 ;;;t \index{INSTANCEOF}
582 ; (INSTANCEOF {value})
585 ; value ::= a ParenScript expression
587 ;;; The single argument expressions `delete', `void', `typeof',
588 ;;; `instanceof' and `new' are generated by the forms `DELETE',
589 ;;; `VOID', `TYPEOF', `INSTANCEOF' and `NEW'. They all take a
590 ;;; ParenScript expression.
592 (delete (new (*foobar 2 3 4))) => delete new Foobar(2, 3, 4)
594 (if (= (typeof blorg) *string)
595 (alert (+ "blorg is a string: " blorg))
596 (alert "blorg is not a string"))
597 => if (typeof blorg == String) {
598 alert('blorg is a string: ' + blorg);
600 alert('blorg is not a string');
603 ;;;# Conditional Statements
604 ;;;t \index{conditional statements}
608 ;;;t \index{conditionals}
610 ; (IF conditional then {else})
611 ; (WHEN condition then)
612 ; (UNLESS condition then)
614 ; condition ::= a ParenScript expression
615 ; then ::= a ParenScript statement in statement context, a
616 ; ParenScript expression in expression context
617 ; else ::= a ParenScript statement in statement context, a
618 ; ParenScript expression in expression context
620 ;;; The `IF' form compiles to the `if' javascript construct. An
621 ;;; explicit `PROGN' around the then branch and the else branch is
622 ;;; needed if they consist of more than one statement. When the `IF'
623 ;;; form is used in an expression context, a JavaScript `?', `:'
624 ;;; operator form is generated.
626 (if (blorg.is-correct)
627 (progn (carry-on) (return i))
628 (alert "blorg is not correct!"))
629 => if (blorg.isCorrect()) {
633 alert('blorg is not correct!');
636 (+ i (if (blorg.add-one) 1 2))
637 => i + (blorg.addOne() ? 1 : 2)
639 ;;; The `WHEN' and `UNLESS' forms can be used as shortcuts for the
642 (when (blorg.is-correct)
645 => if (blorg.isCorrect()) {
650 (unless (blorg.is-correct)
651 (alert "blorg is not correct!"))
652 => if (!blorg.isCorrect()) {
653 alert('blorg is not correct!');
656 ;;;# Variable declaration
657 ;;;t \index{variable}
658 ;;;t \index{variable declaration}
664 ;;;t \index{LEXICAL-LET*}
666 ; (DEFVAR var {value}?)
668 ; (LET* ({var | (var value)}) body)
669 ; (LEXICAL-LET* ({var | (var value)}) body)
671 ; var ::= a Lisp symbol
672 ; value ::= a ParenScript expression
673 ; body ::= a list of ParenScript statements
675 ;;; Parenscript special variables can be declared using the `DEFVAR'
676 ;;; special form, which is similar to its equivalent form in
677 ;;; Lisp. Note that the result is undefined if `DEFVAR' is not used as
678 ;;; a top-level form.
680 (defvar *a* (array 1 2 3)) => var A = [ 1, 2, 3 ]
682 ;;; One feature present in Parenscript that is not part of Common Lisp
683 ;;; are lexically-scoped global variables, which are declared using
684 ;;; the `VAR' special form.
686 ;;; Parenscript provides two special forms for manipulating local
687 ;;; variables: `LET*' and `LEXICAL-LET*'. Both bind their variable
688 ;;; lists sequentially, as indicated by the '*' at the end of their
689 ;;; names, however `LET*' does so using a simple JavaScript
690 ;;; assignment, while `LEXICAL-LET*' actually introduces a new lexical
691 ;;; environment for the variable bindings by creating and populating a
692 ;;; new object and using it as the lexical context for the JavaScript
696 (let* ((blorg "hallo"))
698 (let* ((blorg "blitzel"))
704 var blorg = 'blitzel';
709 (lexical-let* ((blorg "hallo"))
711 (lexical-let* ((blorg "blitzel"))
715 var newlexicalcontext1 = new Object;
716 newlexicalcontext1['blorg'] = 'hallo';
717 with (newlexicalcontext1) {
723 var newlexicalcontext3 = new Object;
724 newlexicalcontext3['blorg'] = 'blitzel';
725 with (newlexicalcontext3) {
731 ;;; Moreover, beware that scoping rules in Lisp and JavaScript are
732 ;;; quite different. For example, don't rely on closures capturing
733 ;;; local variables in the way that you would normally expect.
735 ;;;# Iteration constructs
736 ;;;t \index{iteration}
737 ;;;t \index{iteration construct}
739 ;;;t \index{array traversal}
740 ;;;t \index{property}
741 ;;;t \index{object property}
748 ; (DO ({var | (var {init}? {step}?)}*) (end-test) body)
749 ; (DOTIMES (var numeric-form) body)
750 ; (DOLIST (var list-form) body)
751 ; (DOEACH (var object) body)
752 ; (WHILE end-test body)
754 ; var ::= a Lisp symbol
755 ; numeric-form ::= a ParenScript expression resulting in a number
756 ; list-form ::= a ParenScript expression resulting in an array
757 ; object ::= a ParenScript expression resulting in an object
758 ; init ::= a ParenScript expression
759 ; step ::= a ParenScript expression
760 ; end-test ::= a ParenScript expression
761 ; body ::= a list of ParenScript statements
763 ;;; The `DO' form, which is similar to its Lisp form, is transformed
764 ;;; into a JavaScript `for' statement. Note that the ParenScript `DO'
765 ;;; form does not have a return value, that is because `for' is a
766 ;;; statement and not an expression in JavaScript.
769 (l (aref blorg i) (aref blorg i)))
770 ((or (= i blorg.length)
771 (eql l "Fumitastic")))
772 (document.write (+ "L is " l)))
773 => for (var i = 0, l = blorg[i];
774 !(i == blorg.length || l
== 'Fumitastic
');
775 i
= i
+ 1, l
= blorg
[i]) {
776 document.write('L is ' + l);
779 ;;; The `DOTIMES' form, which lets a variable iterate from 0 upto an
780 ;;; end value, is a shortcut for `DO'.
782 (dotimes (i blorg.length)
783 (document.write (+ "L is " (aref blorg i))))
784 => for (var i = 0; i < blorg.length; i = i + 1) {
785 document.write('L is ' + blorg[i]);
788 ;;; The `DOLIST' form is a shortcut for iterating over an array. Note
789 ;;; that this form creates temporary variables using a function called
790 ;;; `PS-GENSYM', which is similar to its Lisp counterpart `GENSYM'.
793 (document.write
(+ "L is " l
)))
794 => var tmpArr1
= blorg
;
795 for
(var tmpI2
= 0; tmpI2 < tmpArr1.length;
797 var l
= tmpArr1
[tmpI2];
798 document.write('L is ' + l);
801 ;;; The `DOEACH' form is converted to a `for (var .. in ..)' form in
802 ;;; JavaScript. It is used to iterate over the enumerable properties
806 (document.write (+ i " is " (aref object i))))
807 => for (var i in object) {
808 document.write(i + ' is ' + object[i]);
811 ;;; The `WHILE' form is transformed to the JavaScript form `while',
812 ;;; and loops until a termination test evaluates to false.
814 (while (film.is-not-finished)
815 (this.eat (new *popcorn)))
816 => while (film.isNotFinished()) {
817 this.eat(new Popcorn);
820 ;;;# The `CASE' statement
825 ; (CASE case-value clause*)
827 ; clause ::= (value body) | ((value*) body) | t-clause
828 ; case-value ::= a ParenScript expression
829 ; value ::= a ParenScript expression
830 ; t-clause ::= {t | otherwise | default} body
831 ; body ::= a list of ParenScript statements
833 ;;; The Lisp `CASE' form is transformed to a `switch' statement in
834 ;;; JavaScript. Note that `CASE' is not an expression in
838 ((1 "one") (alert "one"))
840 (t (alert "default clause")))
841 => switch (blorg[i]) {
849 default: alert('default clause');
852 ; (SWITCH case-value clause*)
853 ; clause ::= (value body) | (default body)
855 ;;; The `SWITCH' form is the equivalent to a javascript switch statement.
856 ;;; No break statements are inserted, and the default case is named `DEFAULT'.
857 ;;; The `CASE' form should be prefered in most cases.
859 (switch (aref blorg i)
860 (1 (alert "If I get here"))
861 (2 (alert "I also get here"))
862 (default (alert "I always get here")))
863 => switch (blorg[i]) {
864 case 1: alert('If I get here');
865 case 2: alert('I also get here');
866 default: alert('I always get here');
870 ;;;# The `WITH' statement
872 ;;;t \index{dynamic scope}
879 ; object ::= a ParenScript expression evaluating to an object
880 ; body ::= a list of ParenScript statements
882 ;;; The `WITH' form is compiled to a JavaScript `with' statements, and
883 ;;; adds the object `object' as an intermediary scope objects when
884 ;;; executing the body.
886 (with (create :foo "foo" :i "i")
887 (alert (+ "i is now intermediary scoped: " i)))
888 => with ({ foo : 'foo',
890 alert('i is now intermediary scoped: ' + i);
893 ;;;# The `TRY' statement
897 ;;;t \index{exception}
898 ;;;t \index{error handling}
900 ; (TRY body {(:CATCH (var) body)}? {(:FINALLY body)}?)
902 ; body ::= a list of ParenScript statements
903 ; var ::= a Lisp symbol
905 ;;; The `TRY' form is converted to a JavaScript `try' statement, and
906 ;;; can be used to catch expressions thrown by the `THROW'
907 ;;; form. The body of the catch clause is invoked when an exception
908 ;;; is catched, and the body of the finally is always invoked when
909 ;;; leaving the body of the `TRY' form.
913 (alert (+ "an error happened: " error)))
915 (alert "Leaving the try form")))
919 alert('an error happened: ' + error);
921 alert('Leaving the try form');
924 ;;;# The HTML Generator
926 ;;;t \index{HTML generation}
928 ; (PS-HTML html-expression)
930 ;;; The HTML generator of ParenScript is very similar to the htmlgen
931 ;;; HTML generator library included with AllegroServe. It accepts the
932 ;;; same input forms as the AllegroServer HTML generator. However,
933 ;;; non-HTML construct are compiled to JavaScript by the ParenScript
934 ;;; compiler. The resulting expression is a JavaScript expression.
936 (ps-html ((:a :href "foobar") "blorg"))
937 => '<a href=\"foobar\">blorg</a>'
939 (ps-html ((:a :href (generate-a-link)) "blorg"))
940 => '<a href=\"' + generateALink() + '\">blorg</a>'
942 ;;; We can recursively call the ParenScript compiler in an HTML
946 (ps-html ((:a :href "#"
947 :onclick (lisp (ps-inline (transport)))) "link")))
948 => document.write('<a href=\"#\" onclick=\"' + 'javascript:transport()' + '\">link</a>')
950 ;;; Forms may be used in attribute lists to conditionally generate
951 ;;; the next attribute. In this example the textarea is sometimes disabled.
953 (let* ((disabled nil)
955 (setf element.inner-h-t-m-l
956 (ps-html ((:textarea (or disabled (not authorized)) :disabled "disabled")
958 => var disabled = null;
959 var authorized = true;
962 + (disabled || !authorized ? ' disabled=\"' + 'disabled' + '\"' : '')
963 + '>Edit me</textarea>';
967 ;;;t \index{macrology}
968 ;;;t \index{DEFPSMACRO}
969 ;;;t \index{MACROLET}
970 ;;;t \index{SYMBOL-MACROLET}
971 ;;;t \index{PS-GENSYM}
972 ;;;t \index{compiler}
974 ; (DEFPSMACRO name lambda-list macro-body)
975 ; (MACROLET ({name lambda-list macro-body}*) body)
976 ; (SYMBOL-MACROLET ({name macro-body}*) body)
977 ; (PS-GENSYM {string})
979 ; name ::= a Lisp symbol
980 ; lambda-list ::= a lambda list
981 ; macro-body ::= a Lisp body evaluating to ParenScript code
982 ; body ::= a list of ParenScript statements
983 ; string ::= a string
985 ;;; ParenScript can be extended using macros, just like Lisp can be
986 ;;; extended using Lisp macros. Using the special Lisp form
987 ;;; `DEFPSMACRO', the ParenScript language can be
988 ;;; extended. `DEFPSMACRO' adds the new macro to the toplevel macro
989 ;;; environment, which is always accessible during ParenScript
990 ;;; compilation. For example, the `1+' and `1-' operators are
991 ;;; implemented using macros.
993 (defpsmacro 1- (form)
996 (defpsmacro 1+ (form)
999 ;;; A more complicated ParenScript macro example is the implementation
1000 ;;; of the `DOLIST' form (note how `PS-GENSYM', the ParenScript of
1001 ;;; `GENSYM', is used to generate new ParenScript variable names):
1003 (defpsmacro dolist (i-array &rest body)
1004 (let ((var (first i-array))
1005 (array (second i-array))
1006 (arrvar (ps-gensym "arr"))
1007 (idx (ps-gensym "i")))
1008 `(let* ((,arrvar ,array))
1009 (do ((,idx 0 (incf ,idx)))
1010 ((>= ,idx (slot-value ,arrvar 'length)))
1011 (let* ((,var (aref ,arrvar ,idx)))
1014 ;;; Macros can be defined in ParenScript code itself (as opposed to
1015 ;;; from Lisp) by using the ParenScript `MACROLET' and `DEFMACRO'
1018 ;;; ParenScript also supports the use of macros defined in the
1019 ;;; underlying Lisp environment. Existing Lisp macros can be imported
1020 ;;; into the ParenScript macro environment by
1021 ;;; `IMPORT-MACROS-FROM-LISP'. This functionality enables code sharing
1022 ;;; between ParenScript and Lisp, and is useful in debugging since the
1023 ;;; full power of Lisp macroexpanders, editors and other supporting
1024 ;;; facilities can be used. However, it is important to note that the
1025 ;;; macroexpansion of Lisp macros and ParenScript macros takes place
1026 ;;; in their own respective environments, and many Lisp macros
1027 ;;; (especially those provided by the Lisp implementation) expand into
1028 ;;; code that is not usable by ParenScript. To make it easy for users
1029 ;;; to take advantage of these features, two additional macro
1030 ;;; definition facilities are provided by ParenScript: `DEFMACRO/PS'
1031 ;;; and `DEFMACRO+PS'. `DEFMACRO/PS' defines a Lisp macro and then
1032 ;;; imports it into the ParenScript macro environment, while
1033 ;;; `DEFMACRO+PS' defines two macros with the same name and expansion,
1034 ;;; one in ParenScript and one in Lisp. `DEFMACRO+PS' is used when the
1035 ;;; full 'macroexpand' of the Lisp macro yields code that cannot be
1036 ;;; used by ParenScript.
1038 ;;; ParenScript also supports symbol macros, which can be introduced
1039 ;;; using the ParenScript form `SYMBOL-MACROLET'.For example, the
1040 ;;; ParenScript `WITH-SLOTS' is implemented using symbol macros.
1042 (defjsmacro with-slots (slots object &rest body)
1043 `(symbol-macrolet ,(mapcar #'(lambda (slot)
1044 `(,slot '(slot-value ,object ',slot)))
1049 ;;;# The ParenScript namespace system
1050 ;;;t \index{package}
1051 ;;;t \index{namespace}
1052 ;;;t \index{PS-PACKAGE-PREFIX}
1054 ; (setf (PS-PACKAGE-PREFIX package-designator) string)
1056 ;;; Although JavaScript does not offer namespacing or a package
1057 ;;; system, ParenScript does provide a namespace mechanism for
1058 ;;; generated JavaScript by integrating with the Common Lisp package
1059 ;;; system. Since ParenScript code is normally read in by the Lisp
1060 ;;; reader, all symbols (except for uninterned ones, ie - those
1061 ;;; specified with the #: reader macro) have a Lisp package. By
1062 ;;; default, no packages are prefixed. You can specify that symbols in
1063 ;;; a particular package receive a prefix when translated to
1064 ;;; JavaScript with the `PS-PACKAGE-PREFIX' place.
1066 (defpackage "MY-LIBRARY"
1067 (:use #:parenscript))
1068 (setf (ps-package-prefix :my-library) "my_library_")
1070 (defun my-library::library-function (x y)
1072 -> function my_library_libraryFunction(x, y) {
1076 ;;;# Identifier obfuscation
1077 ;;;t \index{obfuscation}
1078 ;;;t \index{identifiers}
1079 ;;;t \index{OBFUSCATE-PACKAGE}
1080 ;;;t \index{UNOBFUSCATE-PACKAGE}
1082 ; (OBFUSCATE-PACKAGE package-designator)
1083 ; (UNOBFUSCATE-PACKAGE package-designator)
1085 ;;; Similar to the namespace mechanism, ParenScript provides a
1086 ;;; facility to generate obfuscated identifiers in certain Lisp
1089 (defpackage "OBFUSCATE-ME")
1090 (obfuscate-package :obfuscate-me)
1092 (defun obfuscate-me::library-function2 (a b obfuscate-me::foo)
1093 (+ a (my-library::library-function b obfuscate-me::foo)))
1095 ;;; The obfuscation and namespace facilities can be used on packages
1096 ;;; at the same time.
1098 ;;;# The ParenScript Compiler
1099 ;;;t \index{compiler}
1100 ;;;t \index{ParenScript compiler}
1101 ;;;t \index{COMPILE-SCRIPT}
1104 ;;;t \index{PS-INLINE}
1106 ;;;t \index{nested compilation}
1108 ; (COMPILE-SCRIPT script-form &key (output-stream nil))
1111 ; (PS-INLINE &body body)
1112 ; (LISP &body lisp-forms)
1114 ; body ::= ParenScript statements comprising an implicit `PROGN'
1116 ;;; For static ParenScript code, the macros `PS' and `PS-INLINE',
1117 ;;; avoid the need to quote the ParenScript expression. `PS*' and
1118 ;;; `COMPILE-SCRIPT' evaluate their arguments. All these forms except
1119 ;;; for `COMPILE-SCRIPT' treat the given forms as an implicit
1120 ;;; `PROGN'. `PS' and `PS*' return a string of the compiled body,
1121 ;;; while `COMPILE-SCRIPT' takes an optional output-stream parameter
1122 ;;; that can be used to specify a stream to which the generated
1123 ;;; JavaScript will be written. `PS-INLINE' generates a string that
1124 ;;; can be used in HTML node attributes.
1126 ;;; ParenScript can also call out to arbitrary Lisp code at
1127 ;;; compile-time using the special form `LISP'. This is typically used
1128 ;;; to insert the values of Lisp special variables into ParenScript
1129 ;;; code at compile-time, and can also be used to make nested calls to
1130 ;;; the ParenScript compiler, which comes in useful when you want to
1131 ;;; use the result of `PS-INLINE' in `PS-HTML' forms, for
1132 ;;; example. Alternatively the same thing can be accomplished by
1133 ;;; constructing ParenScript programs as lists and passing them to
1134 ;;; `PS*' or `COMPILE-SCRIPT'.