Change regex to return Result

[eeue56]

Changed the Regex.regex function to return a Result as per #378 and updated and added tests to this effect. I haven't changed any of the documentation for any other function in Regex.elm, as I feel that rtfeldman's comment on providing a built-in regex syntax needs to be discussed further - certainly it makes code more bulky and there is no way to create a Regex without the regex function.

[rtfeldman]

The more I think about it, the more I like this idea. You can use it to implement the current behavior by using Debug.crash to handle the Err case, which could be offered as a convenience function like regexOrCrash

[rtfeldman]

The more I think about it, the more I like this idea. You can use it to implement the current behavior by using Debug.crash to handle the Err case, which could be offered as a convenience function like regexOrCrash

[eeue56]

Yeah, that's true. I like the Debug.crash approach

[eeue56]

Yeah, that's true. I like the Debug.crash approach

[robertjlooby]

Has any more thought been given to making this change?

[robertjlooby]

Has any more thought been given to making this change?

[tmcw]

minor nitpick that you could express this more succinctly as

return Result.Ok(new RegExp(raw, 'g'));

Here, and avoid using the temporary variable - the code would have the same behavior since new RegExp(raw, 'g') is evaluated first, would throw, and not instantiate a Result.Ok

[tmcw]

Yep, as I posted on the other ticket, I 2nd this approach as flexible and lower-impact than a syntax extension.

[tmcw]

Yep, as I posted on the other ticket, I 2nd this approach as flexible and lower-impact than a syntax extension.

[seanhess]

This would be very helpful to me for the project I am currently working on. Right now we are blocked without it.

[seanhess]

This would be very helpful to me for the project I am currently working on. Right now we are blocked without it.

[eeue56]

@seanhess here's how to unblock you:

• Create a function that looks like this:

var isValidRegex = function(regex, modifiers){
  try {
    new RegExp(regex, modifiers);
  } catch (e) {
    return [regex, false];
  }

  return [regex, true];
}

• Make a port that looks like validateRegex : Cmd String
• Make a port that looks like isValidRegex : Sub (String, Bool)

If you really want, it's trivial to introduce this as a native function into your project. Don't let yourself get blocked on this! it's a trivial issue to solve :)

[eeue56]

@seanhess here's how to unblock you:

• Create a function that looks like this:

var isValidRegex = function(regex, modifiers){
  try {
    new RegExp(regex, modifiers);
  } catch (e) {
    return [regex, false];
  }

  return [regex, true];
}

• Make a port that looks like validateRegex : Cmd String
• Make a port that looks like isValidRegex : Sub (String, Bool)

If you really want, it's trivial to introduce this as a native function into your project. Don't let yourself get blocked on this! it's a trivial issue to solve :)

[seanhess]

@eeue56 ssh, you're removing the imperative to get this merged ;D

Thanks though, that's a great workaround! I forget that native modules are an option for end applications since they can't be published.

[seanhess]

@eeue56 ssh, you're removing the imperative to get this merged ;D

Thanks though, that's a great workaround! I forget that native modules are an option for end applications since they can't be published.

[evancz]

Tracking in #722. These changes are quite easy, so I don't think a PR is needed. Just need to figure out the appropriate time to actually make a change like this.

[evancz]

Tracking in #722. These changes are quite easy, so I don't think a PR is needed. Just need to figure out the appropriate time to actually make a change like this.