scut = super cut Like the hair cutting chain and like a better version of the srfi cut macro.
Jay Sent from my iPhone On Aug 14, 2010, at 3:02 PM, Jon Rafkind <[email protected]> wrote: > Your library looks cool.. definately has more features than what I made. What > does 'scut' mean though? s-cut ? > > On 08/14/2010 09:20 AM, Jay McCarthy wrote: >> This is very similar to supercut: >> >> http://github.com/jeapostrophe/exp/blob/master/scut.ss >> >> scut allows you to put any expression inside it and it will turn it >> into a function. The arguments come from use of _. If you have _i then >> it will be the ith argument. If you have _string then the function >> will take a "string" keyword argument. The function takes as many >> arguments as the maximum i you use inside it. Finally, _... gives you >> the rest arg. The bottom of that file has many examples, here are a >> few: >> >> ((scut _0) 1) => 1 >> >> ((scut (+ _0 (/ _1 _2))) >> 1 2 3) >> => (+ 1 (/ 2 3)) >> >> ((scut (+ _lhs _lhs _rhs)) #:lhs 1 #:rhs 2) >> => 4 >> >> ((scut (apply + _0 _...)) >> 1 2 3) >> => 6 >> >> On Fri, Aug 13, 2010 at 11:01 PM, Jon Rafkind<[email protected]> wrote: >>> I came up with this little hack that lets you avoid giving an explicit >>> argument list to functions. Arguments are discovered by usages of >>> underscores followed by a number, like _1 and _2. Partly inspired by scala; >>> sure to make your blood boil if you love hygiene. >>> >>> ;;; usage >>> (define/implicit foo1 (printf "~a ~a ~a\n" _8 _9 _8)) >>> (foo1 5 12) >>> >>> ;;; code >>> #lang racket/base >>> >>> (require (for-syntax racket/base >>> racket/list >>> syntax/parse >>> ) >>> racket/stxparam) >>> >>> (define-syntax-rule (implicits all thing ...) >>> (begin >>> (define-syntax-parameter thing (lambda (stx) >>> (raise-syntax-error #f (format "~a can only >>> be used in a >>> define/implicit function" 'thing)))) >>> ... >>> (provide thing ...) >>> (define-for-syntax all (list #'thing ...)))) >>> >>> (implicits all-implicits _1 _2 _3 _4 _5 _6 _7 _8 _9 _10) >>> >>> (provide define/implicit lambda/implicit) >>> (define-syntax (lambda/implicit stx) >>> (define (find-implicits stx) >>> (define-syntax-class implicit >>> [pattern x:identifier >>> #:when (ormap (lambda (y) >>> (free-identifier=? y #'x)) >>> all-implicits)]) >>> (remove-duplicates >>> (filter values >>> (syntax-parse stx >>> [x:implicit (list #'x)] >>> [(x ...) (apply append (map find-implicits (syntax->list #'(x >>> ...))))] >>> [else (list #f)])) >>> free-identifier=?)) >>> (syntax-parse stx >>> [(_ body ...) >>> (define implicit-arguments (find-implicits stx)) >>> (with-syntax ([(new-arg ...) (generate-temporaries implicit-arguments)] >>> [(implicit ...) implicit-arguments]) >>> #'(lambda (new-arg ...) >>> (syntax-parameterize ([implicit (make-rename-transformer >>> #'new-arg)] ...) >>> body ...)))])) >>> >>> (define-syntax-rule (define/implicit name body ...) >>> (define name (lambda/implicit body ...))) >>> >>> _________________________________________________ >>> For list-related administrative tasks: >>> http://lists.racket-lang.org/listinfo/users >>> >> >> > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
