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+
84 ABSTRACT AND AREF ARRAY BOOLEAN BREAK BYTE CASE CATCH CC-IF CHAR CLASS
85 COMMA CONST CONTINUE CREATE DEBUGGER DECF DEFAULT DEFUN DEFVAR DELETE
86 DO DOEACH DOLIST DOTIMES DOUBLE ELSE ENUM EQL EXPORT EXTENDS FALSE
87 FINAL FINALLY FLOAT FLOOR FOR FUNCTION GOTO IF IMPLEMENTS IMPORT IN INCF
88 INSTANCEOF INT INTERFACE JS LAMBDA LET LISP LIST LONG MAKE-ARRAY NATIVE NEW
89 NIL NOT OR PACKAGE PRIVATE PROGN PROTECTED PUBLIC RANDOM REGEX RETURN
90 SETF SHORT SLOT-VALUE STATIC SUPER SWITCH SYMBOL-MACROLET SYNCHRONIZED T
91 THIS THROW THROWS TRANSIENT TRY TYPEOF UNDEFINED UNLESS VAR VOID VOLATILE
92 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 parenthized,
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}
479 ;;;t \index{assignment operator}
483 ; lhs ::= a ParenScript left hand side expression
484 ; rhs ::= a ParenScript expression
486 ;;; Assignment is done using the `SETF' form, which is transformed
487 ;;; into a series of assignments using the JavaScript `=' operator.
491 (setf a 2 b 3 c 4 x (+ a b c))
497 ;;; The `SETF' form can transform assignments of a variable with an
498 ;;; operator expression using this variable into a more "efficient"
499 ;;; assignment operator form. For example:
501 (setf a (1+ a)) => a++;
503 (setf a (+ a 2 3 4 a)) => a += 2 + 3 + 4 + a;
505 (setf a (- 1 a)) => a = 1 - a;
507 ;;;# Single argument statements
508 ;;;t \index{single-argument statement}
512 ;;;t \index{function}
517 ; value ::= a ParenScript expression
519 ;;; The single argument statements `return' and `throw' are generated
520 ;;; by the form `RETURN' and `THROW'. `THROW' has to be used inside a
521 ;;; `TRY' form. `RETURN' is used to return a value from a function
524 (return 1) => return 1
526 (throw "foobar") => throw 'foobar'
528 ;;;# Single argument expression
529 ;;;t \index{single-argument expression}
530 ;;;t \index{object creation}
531 ;;;t \index{object deletion}
535 ;;;t \index{INSTANCEOF}
542 ; (INSTANCEOF {value})
545 ; value ::= a ParenScript expression
547 ;;; The single argument expressions `delete', `void', `typeof',
548 ;;; `instanceof' and `new' are generated by the forms `DELETE',
549 ;;; `VOID', `TYPEOF', `INSTANCEOF' and `NEW'. They all take a
550 ;;; ParenScript expression.
552 (delete (new (*foobar 2 3 4))) => delete new Foobar(2, 3, 4)
554 (if (= (typeof blorg) *string)
555 (alert (+ "blorg is a string: " blorg))
556 (alert "blorg is not a string"))
557 => if (typeof blorg == String) {
558 alert('blorg is a string: ' + blorg);
560 alert('blorg is not a string');
563 ;;;# Conditional Statements
564 ;;;t \index{conditional statements}
568 ;;;t \index{conditionals}
570 ; (IF conditional then {else})
571 ; (WHEN condition then)
572 ; (UNLESS condition then)
574 ; condition ::= a ParenScript expression
575 ; then ::= a ParenScript statement in statement context, a
576 ; ParenScript expression in expression context
577 ; else ::= a ParenScript statement in statement context, a
578 ; ParenScript expression in expression context
580 ;;; The `IF' form compiles to the `if' javascript construct. An
581 ;;; explicit `PROGN' around the then branch and the else branch is
582 ;;; needed if they consist of more than one statement. When the `IF'
583 ;;; form is used in an expression context, a JavaScript `?', `:'
584 ;;; operator form is generated.
586 (if (blorg.is-correct)
587 (progn (carry-on) (return i))
588 (alert "blorg is not correct!"))
589 => if (blorg.isCorrect()) {
593 alert('blorg is not correct!');
596 (+ i (if (blorg.add-one) 1 2))
597 => i + (blorg.addOne() ? 1 : 2)
599 ;;; The `WHEN' and `UNLESS' forms can be used as shortcuts for the
602 (when (blorg.is-correct)
605 => if (blorg.isCorrect()) {
610 (unless (blorg.is-correct)
611 (alert "blorg is not correct!"))
612 => if (!blorg.isCorrect()) {
613 alert('blorg is not correct!');
616 ;;;# Variable declaration
617 ;;;t \index{variable}
618 ;;;t \index{variable declaration}
624 ; (DEFVAR var {value}?)
625 ; (LET ({var | (var value)) body)
627 ; var ::= a Lisp symbol
628 ; value ::= a ParenScript expression
629 ; body ::= a list of ParenScript statements
631 ;;; Variables (either local or global) can be declared using the
632 ;;; `DEFVAR' form, which is similar to its equivalent form in
633 ;;; Lisp. The `DEFVAR' is converted to "var ... = ..." form in
636 (defvar *a* (array 1 2 3)) => var A = [ 1, 2, 3 ]
639 (progn (defvar blorg "hallo")
641 (progn (defvar blorg "blitzel")
647 var blorg = 'blitzel';
651 ;;; A more lispy way to declare local variable is to use the `LET'
652 ;;; form, which is similar to its Lisp form.
655 (let ((blorg "hallo"))
657 (let ((blorg "blitzel"))
663 var blorg = 'blitzel';
667 ;;; However, beware that scoping in Lisp and JavaScript are quite
668 ;;; different. For example, don't rely on closures capturing local
669 ;;; variables in the way you'd think they would.
671 ;;;# Iteration constructs
672 ;;;t \index{iteration}
673 ;;;t \index{iteration construct}
675 ;;;t \index{array traversal}
676 ;;;t \index{property}
677 ;;;t \index{object property}
684 ; (DO ({var | (var {init}? {step}?)}*) (end-test) body)
685 ; (DOTIMES (var numeric-form) body)
686 ; (DOLIST (var list-form) body)
687 ; (DOEACH (var object) body)
688 ; (WHILE end-test body)
690 ; var ::= a Lisp symbol
691 ; numeric-form ::= a ParenScript expression resulting in a number
692 ; list-form ::= a ParenScript expression resulting in an array
693 ; object ::= a ParenScript expression resulting in an object
694 ; init ::= a ParenScript expression
695 ; step ::= a ParenScript expression
696 ; end-test ::= a ParenScript expression
697 ; body ::= a list of ParenScript statements
699 ;;; The `DO' form, which is similar to its Lisp form, is transformed
700 ;;; into a JavaScript `for' statement. Note that the ParenScript `DO'
701 ;;; form does not have a return value, that is because `for' is a
702 ;;; statement and not an expression in JavaScript.
705 (l (aref blorg i) (aref blorg i)))
706 ((or (= i blorg.length)
707 (eql l "Fumitastic")))
708 (document.write (+ "L is " l)))
709 => for (var i = 0, l = blorg[i];
710 !(i == blorg.length || l
== 'Fumitastic
');
711 i
= i
+ 1, l
= blorg
[i]) {
712 document.write('L is ' + l);
715 ;;; The `DOTIMES' form, which lets a variable iterate from 0 upto an
716 ;;; end value, is a shortcut for `DO'.
718 (dotimes (i blorg.length)
719 (document.write (+ "L is " (aref blorg i))))
720 => for (var i = 0; i < blorg.length; i = i + 1) {
721 document.write('L is ' + blorg[i]);
724 ;;; The `DOLIST' form is a shortcut for iterating over an array. Note
725 ;;; that this form creates temporary variables using a function called
726 ;;; `PS-GENSYM', which is similar to its Lisp counterpart `GENSYM'.
729 (document.write
(+ "L is " l
)))
730 => var tmpArr1
= blorg
;
731 for
(var tmpI2
= 0; tmpI2 < tmpArr1.length;
733 var l
= tmpArr1
[tmpI2];
734 document.write('L is ' + l);
737 ;;; The `DOEACH' form is converted to a `for (var .. in ..)' form in
738 ;;; JavaScript. It is used to iterate over the enumerable properties
742 (document.write (+ i " is " (aref object i))))
743 => for (var i in object) {
744 document.write(i + ' is ' + object[i]);
747 ;;; The `WHILE' form is transformed to the JavaScript form `while',
748 ;;; and loops until a termination test evaluates to false.
750 (while (film.is-not-finished)
751 (this.eat (new *popcorn)))
752 => while (film.isNotFinished()) {
753 this.eat(new Popcorn);
756 ;;;# The `CASE' statement
761 ; (CASE case-value clause*)
763 ; clause ::= (value body) | ((value*) body) | t-clause
764 ; case-value ::= a ParenScript expression
765 ; value ::= a ParenScript expression
766 ; t-clause ::= {t | otherwise | default} body
767 ; body ::= a list of ParenScript statements
769 ;;; The Lisp `CASE' form is transformed to a `switch' statement in
770 ;;; JavaScript. Note that `CASE' is not an expression in
774 ((1 "one") (alert "one"))
776 (t (alert "default clause")))
777 => switch (blorg[i]) {
785 default: alert('default clause');
788 ; (SWITCH case-value clause*)
789 ; clause ::= (value body) | (default body)
791 ;;; The `SWITCH' form is the equivalent to a javascript switch statement.
792 ;;; No break statements are inserted, and the default case is named `DEFAULT'.
793 ;;; The `CASE' form should be prefered in most cases.
795 (switch (aref blorg i)
796 (1 (alert "If I get here"))
797 (2 (alert "I also get here"))
798 (default (alert "I always get here")))
799 => switch (blorg[i]) {
800 case 1: alert('If I get here');
801 case 2: alert('I also get here');
802 default: alert('I always get here');
806 ;;;# The `WITH' statement
808 ;;;t \index{dynamic scope}
815 ; object ::= a ParenScript expression evaluating to an object
816 ; body ::= a list of ParenScript statements
818 ;;; The `WITH' form is compiled to a JavaScript `with' statements, and
819 ;;; adds the object `object' as an intermediary scope objects when
820 ;;; executing the body.
822 (with (create :foo "foo" :i "i")
823 (alert (+ "i is now intermediary scoped: " i)))
824 => with ({ foo : 'foo',
826 alert('i is now intermediary scoped: ' + i);
829 ;;;# The `TRY' statement
833 ;;;t \index{exception}
834 ;;;t \index{error handling}
836 ; (TRY body {(:CATCH (var) body)}? {(:FINALLY body)}?)
838 ; body ::= a list of ParenScript statements
839 ; var ::= a Lisp symbol
841 ;;; The `TRY' form is converted to a JavaScript `try' statement, and
842 ;;; can be used to catch expressions thrown by the `THROW'
843 ;;; form. The body of the catch clause is invoked when an exception
844 ;;; is catched, and the body of the finally is always invoked when
845 ;;; leaving the body of the `TRY' form.
849 (alert (+ "an error happened: " error)))
851 (alert "Leaving the try form")))
855 alert('an error happened: ' + error);
857 alert('Leaving the try form');
860 ;;;# The HTML Generator
862 ;;;t \index{HTML generation}
864 ;;;t \index{CSS generation}
867 ; (HTML html-expression)
869 ;;; The HTML generator of ParenScript is very similar to the HTML
870 ;;; generator included in AllegroServe. It accepts the same input
871 ;;; forms as the AllegroServer HTML generator. However, non-HTML
872 ;;; construct are compiled to JavaScript by the ParenScript
873 ;;; compiler. The resulting expression is a JavaScript expression.
875 (html ((:a :href "foobar") "blorg"))
876 => '<a href=\"foobar\">blorg</a>'
878 (html ((:a :href (generate-a-link)) "blorg"))
879 => '<a href=\"' + generateALink() + '\">blorg</a>'
881 ;;; We can recursively call the JS compiler in a HTML expression.
885 :onclick (ps-inline (transport))) "link")))
886 => document.write('<a href=\"#\" onclick=\"' + 'javascript:transport();' + '\">link</a>')
888 ;;; Forms may be used in attribute lists to conditionally generate
889 ;;; the next attribute. In this example the textarea is sometimes disabled.
893 (setf element.inner-h-t-m-l
894 (html ((:textarea (or disabled (not authorized)) :disabled "disabled")
896 => var disabled = null;
897 var authorized = true;
900 + (disabled || !authorized ? ' disabled=\"' + 'disabled' + '\"' : '')
901 + '>Edit me</textarea>';
903 ; (CSS-INLINE css-expression)
905 ;;; Stylesheets can also be created in ParenScript.
907 (css-inline :color "red"
908 :font-size "x-small")
909 => 'color:red;font-size:x-small'
911 (defun make-color-div(color-name)
912 (return (html ((:div :style (css-inline :color color-name))
913 color-name " looks like this."))))
914 => function makeColorDiv(colorName) {
915 return '<div style=\"' + ('color:' + colorName) + '\">' + colorName
916 + ' looks like this.</div>';
921 ;;;t \index{macrology}
922 ;;;t \index{DEFJSMACRO}
923 ;;;t \index{MACROLET}
924 ;;;t \index{SYMBOL-MACROLET}
925 ;;;t \index{JS-GENSYM}
926 ;;;t \index{compiler}
928 ; (DEFJSMACRO name lambda-list macro-body)
929 ; (MACROLET ({name lambda-list macro-body}*) body)
930 ; (SYMBOL-MACROLET ({name macro-body}*) body)
931 ; (JS-GENSYM {string}?)
933 ; name ::= a Lisp symbol
934 ; lambda-list ::= a lambda list
935 ; macro-body ::= a Lisp body evaluating to ParenScript code
936 ; body ::= a list of ParenScript statements
937 ; string ::= a string
939 ;;; ParenScript can be extended using macros, just like Lisp can be
940 ;;; extended using Lisp macros. Using the special Lisp form
941 ;;; `DEFJSMACRO', the ParenScript language can be
942 ;;; extended. `DEFJSMACRO' adds the new macro to the toplevel macro
943 ;;; environment, which is always accessible during ParenScript
944 ;;; compilation. For example, the `1+' and `1-' operators are
945 ;;; implemented using macros.
947 (defjsmacro 1- (form)
950 (defjsmacro 1+ (form)
953 ;;; A more complicated ParenScript macro example is the implementation
954 ;;; of the `DOLIST' form (note how `JS-GENSYM', the ParenScript of
955 ;;; `GENSYM', is used to generate new ParenScript variable names):
957 (defpsmacro dolist (i-array &rest body)
958 (let ((var (first i-array))
959 (array (second i-array))
960 (arrvar (js-gensym "arr"))
961 (idx (js-gensym "i")))
962 `(let ((,arrvar ,array))
963 (do ((,idx 0 (incf ,idx)))
964 ((>= ,idx (slot-value ,arrvar 'length)))
965 (let ((,var (aref ,arrvar ,idx)))
968 ;;; Macros can be defined in ParenScript itself (as opposed to Lisp)
969 ;;; by using the ParenScript `MACROLET' and 'DEFMACRO' forms.
971 ;;; ParenScript also supports the use of macros defined in the
972 ;;; underlying Lisp. Existing Lisp macros can be imported into the
973 ;;; ParenScript macro environment by 'IMPORT-MACROS-FROM-LISP'. This
974 ;;; functionality enables code sharing between ParenScript and Lisp,
975 ;;; and is useful in debugging since the full power of Lisp
976 ;;; macroexpanders, editors and other supporting facilities can be
977 ;;; used. However, it is important to note that the macroexpansion of
978 ;;; Lisp macros and ParenScript macros takes place in their own
979 ;;; respective environments, and many Lisp macros (especially those
980 ;;; provided by the Lisp implementation) expand into code that is not
981 ;;; usable by ParenScript. To make it easy for users to take advantage
982 ;;; of these features, two additional macro definition facilities are
983 ;;; provided by ParenScript: 'DEFMACRO/JS' and
984 ;;; 'DEFMACRO+JS'. 'DEFMACRO/JS' defines a Lisp macro and then imports
985 ;;; it into the ParenScript macro environment, while 'DEFMACRO+JS'
986 ;;; defines two macros with the same name and expansion, one in
987 ;;; ParenScript and one in Lisp. 'DEFMACRO+JS' is used when the full
988 ;;; 'macroexpand' of the Lisp macro yields code that cannot be used by
991 ;;; ParenScript also supports symbol macros, which can be introduced
992 ;;; using the ParenScript form `SYMBOL-MACROLET'. A new macro
993 ;;; environment is created and added to the current macro environment
994 ;;; list while compiling the body of the `SYMBOL-MACROLET' form. For
995 ;;; example, the ParenScript `WITH-SLOTS' is implemented using symbol
998 (defjsmacro with-slots (slots object &rest body)
999 `(symbol-macrolet ,(mapcar #'(lambda (slot)
1000 `(,slot '(slot-value ,object ',slot)))
1004 ;;;# The ParenScript Compiler
1005 ;;;t \index{compiler}
1006 ;;;t \index{ParenScript compiler}
1007 ;;;t \index{JS-COMPILE}
1008 ;;;t \index{JS-TO-STRINGS}
1009 ;;;t \index{JS-TO-STATEMENT-STRINGS}
1010 ;;;t \index{JS-TO-STRING}
1011 ;;;t \index{JS-TO-LINE}
1013 ;;;t \index{JS-INLINE}
1014 ;;;t \index{JS-FILE}
1015 ;;;t \index{JS-SCRIPT}
1016 ;;;t \index{nested compilation}
1019 ; (JS-TO-STRINGS compiled-expr position)
1020 ; (JS-TO-STATEMENT-STRINGS compiled-expr position)
1022 ; compiled-expr ::= a compiled ParenScript expression
1023 ; position ::= a column number
1025 ; (JS-TO-STRING expression)
1026 ; (JS-TO-LINE expression)
1028 ; expression ::= a Lisp list of ParenScript code
1035 ; body ::= a list of ParenScript statements
1037 ;;; The ParenScript compiler can be invoked from withing Lisp and from
1038 ;;; within ParenScript itself. The primary API function is
1039 ;;; `JS-COMPILE', which takes a list of ParenScript, and returns an
1040 ;;; internal object representing the compiled ParenScript.
1042 (js-compile '(foobar 1 2))
1043 => #<JS::FUNCTION-CALL {584AA5DD}>
1045 ;;; This internal object can be transformed to a string using the
1046 ;;; methods `JS-TO-STRINGS' and `JS-TO-STATEMENT-STRINGS', which
1047 ;;; interpret the ParenScript in expression and in statement context
1048 ;;; respectively. They take an additional parameter indicating the
1049 ;;; start-position on a line (please note that the indentation code is
1050 ;;; not perfect, and this string interface will likely be
1051 ;;; changed). They return a list of strings, where each string
1052 ;;; represents a new line of JavaScript code. They can be joined
1053 ;;; together to form a single string.
1055 (js-to-strings (js-compile '(foobar 1 2)) 0)
1058 ;;; As a shortcut, ParenScript provides the functions `JS-TO-STRING'
1059 ;;; and `JS-TO-LINE', which return the JavaScript string of the
1060 ;;; compiled expression passed as an argument.
1062 (js-to-string '(foobar 1 2))
1065 ;;; For static ParenScript code, the macros `JS', `JS-INLINE',
1066 ;;; `JS-FILE' and `JS-SCRIPT' avoid the need to quote the ParenScript
1067 ;;; expression. All these forms add an implicit `PROGN' form around
1068 ;;; the body. `JS' returns a string of the compiled body, where the
1069 ;;; other expression return an expression that can be embedded in a
1070 ;;; HTML generation construct using the AllegroServe HTML
1071 ;;; generator. `JS-SCRIPT' generates a "SCRIPT" node, `JS-INLINE'
1072 ;;; generates a string to be used in node attributs, and `JS-FILE'
1073 ;;; prints the compiled ParenScript code to the HTML stream.
1075 ;;; These macros are also available inside ParenScript itself, and
1076 ;;; generate strings that can be used inside ParenScript code. Note
1077 ;;; that `JS-INLINE' in ParenScript is not the same `JS-INLINE' form
1078 ;;; as in Lisp, for example. The same goes for the other compilation