Various useful little macros.
Note: since version 2.95, this extension does not support doto anymore. It is provided instead by Moritz Heidkamp's clojurian egg, among other other interesting Clojure macros.
- (let/cc K BODY ...) syntax
Executes BODY ... with K bound to the current-continuation.
- (until TEST BODY ...) syntax
Executes BODY ... repeatedly while the expression TEST returns #f.
- (repeat TIMES BODY ...) syntax
Executes BODY ... TIMES times.
- (repeat* TIMES BODY ...) syntax
Executes BODY ... TIMES times, with the variable it bound to the count-down value.
- (dotimes (VAR TIMES [FINAL]) BODY ...) syntax
Executes BODY ... TIMES times, with the variable VAR bound to the count-up value.
Returns the result of the FINAL expression or (void) when no FINAL expression.
- (while TEST BODY ...) syntax
Executes BODY ... repeatedly until the expression TEST returns #f.
- (while* TEST BODY ...) syntax
Executes BODY ... repeatedly, with the result of TEST bound to the variable it, until the expression TEST returns #f.
- (if* X Y [Z]) syntax
The anaphoric if: if the expression X evaluates to a true value, the expression Y will be executed with the result of X bound to the variable it. If X is false, then Z (if supplied) will be evaluated:
(if* (> 3 1) it) ==> #t (if* (memq 'a '(b a c)) (cdr it) 99) ==> (c) (if* #f it 1) ==> 1 (if* #f #f) ==> #<unspecified>
- (push! X LOC) syntax
(set! LOC (cons X LOC))
Note that LOC may be any settable location.
- (pop! LOC) syntax
Returns the first element from the list stored in the location LOC and sets LOC to the cdr of the previous value.
- (inc! LOC [AMOUNT]) syntax
Equivalent to (set! LOC (+ LOC AMOUNT)). AMOUNT defaults to 1. Returns the new value.
- (dec! LOC [AMOUNT]) syntax
Equivalent to (set! LOC (- LOC AMOUNT)). AMOUNT defaults to 1. Returns the new value.
- (ignore-errors BODY ...) syntax
Evaluates the expressions in BODY .... If any exceptions should be raised during execution of the body, then the exceptions will be caught, and ignore-errors returns #f.
- (begin0 BODY ...) syntax
Evaluates BODY ... just like begin, but instead of returning the last value(s), begin0 returns the result (or the results) of the first expression in BODY ....
- (define-enum ->INT ->SYM ID ...) syntax
Defines an enumeration. The variables ID, ... are bound to the exact integers 0, 1, ... with define-constant. ID may also take the form (ID N), in which case the counter will be set to the exact integer N for that variable, and continue upward normally from there. A procedure named ->INT will be defined that takes a symbols and returns the respective integer. A procedure ->SYM will also be defined that takes an integer and returns the respective symbol (from the set of IDs). If a symbol doesn't map to an integer (or vice versa), #f is returned.
- (define-optionals ((VAR1 DEFAULT1) ...) ARGUMENTS) syntax
Defines the globals VAR1 ... with the values taken from the list ARGUMENTS, or with DEFAULT1 ..., if the list is shorter.
- (define-parameter VAR [VALUE [GUARD]]) syntax
(define VAR (make-parameter VALUE [GUARD]))
VALUE defaults to (void).
- (ignore-values EXP) syntax
Evaluates EXP ignoring any return values. Returns an unspecified value.
- (modify-location LOC PROC) syntax
Expands into a call to PROC with two arguments: a zero-argument procedure for retrieving the value from the settable location LOC and a one argument procedure for setting the value of LOC. Care is taken to evaluate any subforms in LOC only once.
modify-location is intended to create modification macros for generalized locations (as in SRFI-17.
(define-syntax-rule (increment! loc) (modify-location loc (lambda (ref upd) (upd (add1 (ref)))) ) ) (define x (vector 123)) (increment! (vector-ref x (print 0))) ; sets x to #(124) and prints "0" only once
- (modify! LOC PROC) syntax
Modifies the contents of location LOC by applying the procedure PROC to it's contents and setting LOCs to the result. LOC may be any settable location.
(define-macro (increment! loc) `(modify! ,loc add1) )
- (exchange! LOC1 LOC2) syntax
Exchanges the contents of the given locations. LOC1 and LOC2 may be any settable locations.
- (define-syntax-rule (NAME ARGUMENT ...) TEMPLATE) syntax
(define-syntax NAME (syntax-rules () ((_ ARGUMENT ...) TEMPLATE)))
- (ecase EXP ((LITERAL ...) BODY ...) ...) syntax
Similar to case, but signals an error if no clause matches.
- 2.95 Removed doto
- 2.91 Added doto (contributed by Martin DeMello)
- 2.9 inc! and dec! return the new value
- 2.8 added define-syntax-rule
- 2.7 added import-only extension property and allowed optional increment/decrement for inc! and dec!
- 2.6 removed -host option from setup script
- 2.5 Add counter set capability to define-enum [zbigniew]
- 2.4 Added modify! and exchange! [felix]
- 2.3 Added dotimes [by Kon Lovett]
- 2.2 Fixed bug in pop!
- 2.1 Added modify-location and made location-modification macros general for set!table locations
- 2.0 Added some simple looping constructs [by Kon Lovett]
- 1.9 Added while* [by Kon Lovett]
- 1.8 Fixed bug in if* [Thanks to Houman Zolfaghari]
- 1.7 Added ignore-values and define-parameter
- 1.6 Fixed bug in if* [Thanks to Michele Simionato]
- 1.5 removed shift! and rotate!
- 1.4 ignore-errors returns #f on exception
- 1.3 Added missing documentation for define-optionals
- 1.2 Added define-enum [by Alex Shinn]
- 1.1 Added inc! and dec!
- 1.0 Initial release
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