Color field

[ciukstar]

Reference issue #1747

This PR adds a new colorField function to create an html color field (<input type="color">) as described at https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Input/color

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Before submitting your PR, check that you've:

• Bumped the version number
• Documented new APIs with Haddock markup
• Added @since declarations to the Haddocks for new, public APIs

After submitting your PR:

• Update the Changelog.md file with a link to your PR
• Check that CI passes (or if it fails, for reasons unrelated to your change, like CI timeouts)

[schoettl]

Hex numbers in CSS can also be #fff (3 letters). Are you sure that all browsers ever only set 6 letter hex digits?

[ciukstar]

Quoting from https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Input/color:

"The value must be in seven-character hexadecimal notation, meaning the "#" character followed by two digits each representing red, green, and blue, like this: #rrggbb".

It is supposed to cover only HTML, not CSS.
Please let me know if I have to look in other non-HTML specs such as CSS. I'm not sure of this.

[schoettl]

Ah, I guess you're right! BTW, this would be the most official spec for HTML input: https://html.spec.whatwg.org/multipage/input.html#color-state-(type=color)
… the "bookkeeping details" are also interesting.

[jezen]

@ciukstar Thanks for the PR! Looks good to me 👍 I've started running the build on CI for this, and hopefully we can get this over the line for you soon.

[ciukstar]

Hi! I see 14 successful and 4 failed checks. Do I need to do something to make it pass all the checks?

[jezen]

@ciukstar Sorry for the slow response, I've been busy escaping the war in Ukraine.

I'm not sure why those MacOS builds are failing. Perhaps @snoyberg might know?

[snoyberg]

I have no idea why it would have stopped working recently, I'm assuming that it's to do with GitHub Actions upgrading MacOS images. I see this error message:

yesod-bin                        > <command line>: can't load framework: Cocoa (not found)

I'd recommend ignoring the failure for now.