Racket raw strings

Question

In Racket you have to escape backslashes in strings, therefore Windows paths and regexes become verbose.

For example, the regular expression (.*)\1 can be represented with the string "(.*)\\1" or the regexp constant #rx"(.*)\\1"; the \ in the regular expression must be escaped to include it in a string or regexp constant. [Source: Regexp Syntax]

In many languages like Perl and Ruby regexes are supported syntactically /\([a-z]+\)/, in others there are optional raw strings, like in Python r"\([a-z]+\)". It seems that Racket doesn't support raw strings, where you don't need to escape backslashes, natively. Is there any method to implement them, a third-party library, a proposal, whatever?

See also:

• Regular Expressions @ The Racket Guide
• Regular Expressions @ The Racket Reference

Answer 1

As Chris mentioned, a custom reader can do this.

An example of a reader that Racket already supplies, that you could use, is at-exp:

#lang at-exp racket

@~a{C:\Windows\win.ini}
;; "C:\\Windows\\win.ini"

@~a{This is a string
    with newlines.}
;; "This is a\nstring with newlines."

I like to use ~a with this because it converts anything to a string, and it's only two characters to type.

However for your regexp example, you can't use ~a or #rx. Instead you should use regexp:

@regexp{(.*)\1}
;; #rx"(.*)\\1"

In all of these examples, @function{string} is read as (function "string") -- basically. There are some nuances you can read about in the documentation for at-exp and Scribble.