Re: [racket-dev] The `var` pattern in `match`
Having something like the var pattern can be useful for macros that expand into uses of match, if the macro doesn't want to expose that a bound variable will be a match pattern and therefore must not be _ or Granted, there are ways around this, but personally I think it would be nice if match supported this pattern. I would, however, entirely support renaming this pattern to something more obscure, like match:pattern-variable or something, so that unintentional uses stop being a problem. Carl Eastlund On Thu, Nov 29, 2012 at 12:17 AM, Neil Toronto neil.toro...@gmail.comwrote: On 11/28/2012 06:04 PM, David Van Horn wrote: On 11/28/12 7:53 PM, Sam Tobin-Hochstadt wrote: Currently, `match` provides a pattern named `var`, which makes `(var id)` equivalent to `id`, but without special cases for things like `_` and `...`. However, this frequently conflicts with structures that people define, and is rarely used other than accidentally. I'd therefore like to remove it entirely. + (expt 2 (expt 2 (expt 2 (expt 2 2 Since I've never used `var' and it sounds like a great idea to get rid of it, I'll see David's repeated exponential and raise it by \aleph_0. Note that downvotes must now at least sum to \aleph_1 to retain the `var' pattern. One downvote for every real number is sufficient. Neil ⊥ _ Racket Developers list: http://lists.racket-lang.org/**dev http://lists.racket-lang.org/dev _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] The `var` pattern in `match`
+1 On Nov 29, 2012, at 7:31 AM, Carl Eastlund wrote: Having something like the var pattern can be useful for macros that expand into uses of match, if the macro doesn't want to expose that a bound variable will be a match pattern and therefore must not be _ or Granted, there are ways around this, but personally I think it would be nice if match supported this pattern. I would, however, entirely support renaming this pattern to something more obscure, like match:pattern-variable or something, so that unintentional uses stop being a problem. Carl Eastlund On Thu, Nov 29, 2012 at 12:17 AM, Neil Toronto neil.toro...@gmail.com wrote: On 11/28/2012 06:04 PM, David Van Horn wrote: On 11/28/12 7:53 PM, Sam Tobin-Hochstadt wrote: Currently, `match` provides a pattern named `var`, which makes `(var id)` equivalent to `id`, but without special cases for things like `_` and `...`. However, this frequently conflicts with structures that people define, and is rarely used other than accidentally. I'd therefore like to remove it entirely. + (expt 2 (expt 2 (expt 2 (expt 2 2 Since I've never used `var' and it sounds like a great idea to get rid of it, I'll see David's repeated exponential and raise it by \aleph_0. Note that downvotes must now at least sum to \aleph_1 to retain the `var' pattern. One downvote for every real number is sufficient. Neil ⊥ _ Racket Developers list: http://lists.racket-lang.org/dev _ Racket Developers list: http://lists.racket-lang.org/dev smime.p7s Description: S/MIME cryptographic signature _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] The `var` pattern in `match`
On 11/29/12 7:31 AM, Carl Eastlund wrote: Having something like the var pattern can be useful for macros that expand into uses of match, if the macro doesn't want to expose that a bound variable will be a match pattern and therefore must not be _ or Granted, there are ways around this, but personally I think it would be nice if match supported this pattern. I would, however, entirely support renaming this pattern to something more obscure, like match:pattern-variable or something, so that unintentional uses stop being a problem. I think the real solution is to have (whatever name you give) `var' be something that is matched as an identifier and not a literal so that programmers can rename the pattern. But I know from talking with Sam this would be a big change for match. In the meantime, something more obscure than `var' would go a long way toward me not cursing Sam's good name every time I write an AST. David _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] The `var` pattern in `match`
On Thu, Nov 29, 2012 at 10:40 AM, David Van Horn dvanh...@ccs.neu.edu wrote: On 11/29/12 7:31 AM, Carl Eastlund wrote: Having something like the var pattern can be useful for macros that expand into uses of match, if the macro doesn't want to expose that a bound variable will be a match pattern and therefore must not be _ or Granted, there are ways around this, but personally I think it would be nice if match supported this pattern. I would, however, entirely support renaming this pattern to something more obscure, like match:pattern-variable or something, so that unintentional uses stop being a problem. I think the real solution is to have (whatever name you give) `var' be something that is matched as an identifier and not a literal so that programmers can rename the pattern. But I know from talking with Sam this would be a big change for match. Making `var` specifically be matched by binding would be possible -- it would be less of a change than removing it entirely. -- sam th sa...@ccs.neu.edu _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] The `var` pattern in `match`
On 11/29/12 1:45 PM, Sam Tobin-Hochstadt wrote: On Thu, Nov 29, 2012 at 10:40 AM, David Van Horn dvanh...@ccs.neu.edu wrote: On 11/29/12 7:31 AM, Carl Eastlund wrote: Having something like the var pattern can be useful for macros that expand into uses of match, if the macro doesn't want to expose that a bound variable will be a match pattern and therefore must not be _ or Granted, there are ways around this, but personally I think it would be nice if match supported this pattern. I would, however, entirely support renaming this pattern to something more obscure, like match:pattern-variable or something, so that unintentional uses stop being a problem. I think the real solution is to have (whatever name you give) `var' be something that is matched as an identifier and not a literal so that programmers can rename the pattern. But I know from talking with Sam this would be a big change for match. Making `var` specifically be matched by binding would be possible -- it would be less of a change than removing it entirely. I would still like the default to be something other than `var'. (BTW, it looks like `var' is not an indexed term in the docs for match.) David _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] The `var` pattern in `match`
On 11/28/12 7:53 PM, Sam Tobin-Hochstadt wrote: Currently, `match` provides a pattern named `var`, which makes `(var id)` equivalent to `id`, but without special cases for things like `_` and `...`. However, this frequently conflicts with structures that people define, and is rarely used other than accidentally. I'd therefore like to remove it entirely. + (expt 2 (expt 2 (expt 2 (expt 2 2 _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] The `var` pattern in `match`
On 11/28/2012 06:04 PM, David Van Horn wrote: On 11/28/12 7:53 PM, Sam Tobin-Hochstadt wrote: Currently, `match` provides a pattern named `var`, which makes `(var id)` equivalent to `id`, but without special cases for things like `_` and `...`. However, this frequently conflicts with structures that people define, and is rarely used other than accidentally. I'd therefore like to remove it entirely. + (expt 2 (expt 2 (expt 2 (expt 2 2 Since I've never used `var' and it sounds like a great idea to get rid of it, I'll see David's repeated exponential and raise it by \aleph_0. Note that downvotes must now at least sum to \aleph_1 to retain the `var' pattern. One downvote for every real number is sufficient. Neil ⊥ _ Racket Developers list: http://lists.racket-lang.org/dev
