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 > -- Jay McCarthy <[email protected]> Assistant Professor / Brigham Young University http://teammccarthy.org/jay "The glory of God is Intelligence" - D&C 93 _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
