Yesterday, Laurent wrote: > Or better here: @values{C:\Users\Harry\SANSKRIT\GRETIL > ALL\adyappu.htm} to avoid the superfluous ~a operation.
Using `values' is not a good idea since it works only if you don't use nested @s or newlines. If these things are included, you'll end up with a form that is equivalent to (values x y z) and things will probably break in a confusing way. > I've just surprised myself testing @(...){...} and seeing that it > works: @(lambda(x)x){C:\Users\Harry\SANSKRIT\GRETIL ALL\adyappu.htm} That's intentional, and more than that, any form can be used including @-forms, which means that to write a function that takes in two blocks of text you can do something like this: @(define ((foo . text1) . text2) ...stuff...) @@foo{some text}{some more text} (This is a simplified example again, where you just get a single argument, but in the general case you'd have multiple inputs for both texts.) Yesterday, Harry Spier wrote: > > 2) > What am I doing wrong here. -- everything :-) > I'm trying to change the command character from @ to # so that I > can have raw strings containing both \ and @ looking at the racket > documentation here: > http://docs.racket-lang.org/scribble/reader-internals.html?q=at-exp# > %28def._%28%28lib._scribble%2Freader..rkt%29._make-at-readtable%29%29 > [...] It's possible to do that, though you'll need to implement your own reader. Not too hard, since the scribble/reader functionality can build the appropriate table, but two notes before you go that route: 1. Overriding "#" is a bad idea, since it has special meaning in Racket code. Some obvious examples that you'll lose are boolean literals, vector literals, and the convention that "#<" is an unreadable value -- a convention that can lead to copy/paste surprises if broken. 2. If you want to include more free-form text, there's a reader feature that allows you to use customized tokens: @foo|{ some text including @s }| to use nested forms, you'd need to use "|@". If that's not enough, then you can also include more things between the braces and the bars: @foo|==!!=={ even more free text, including @|s etc }==!!| Yesterday, Greg Hendershott wrote: > I have @~a{} in muscle memory because it's handy for a variety of > purposes, including as an alternative to format/printf. > > #lang at-exp racket > > (define x 1) > (define y 10) > > (format "x is ~a, y is ~a, and x + y is ~a" x y (+ x y)) > ;; or > @~a{x is @x, y is @y, and x + y is @(+ x y)} > > ;; both => "x is 1, y is 10, and x + y is 11" Allowing such things was very intentional in the design... The `scribble/text' language goes further in that it allows many more things in the contents for printing. There's no to-string form for it though, since I wasn't sure that it's a good idea -- mostly because people would be tempted to do something like (display @to-string{stuff}) where a long string gets allocated for no good reason. Using `output' instead usually looks like this: (output @list{ anything you want }) since lists are just scanned recursively by `output'. As a side note, this use of lists makes some things very convenient -- instead of tricky code that uses `append-map' or `format's, `string-append's and `~a's, you just use lists, nesting them as much as you want. > p.s. I believe http://www.mail-archive.com/users@racket-lang.org/msg07162.html > predates `~a` being added to Racket. (It does.) -- ((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay: http://barzilay.org/ Maze is Life! ____________________ Racket Users list: http://lists.racket-lang.org/users