Correct setting for JSPT font_features with Iosevka?

[benfrain]

I'm trying to set Iosevka Slab font to have JSPT ligatures using the font_features in my config:

font_features   Iosevka-Slab -calt +JSPT

However, I am still not getting the appropriate ligature of triple equals ===. Here it is in Kitty with that setting:

And here it is in VSCode with that setting turned on:

Am I switching the ligatures on in Kitty correctly? I have tried using the normal and postscript font name here but same result with both.

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I tested it on macOS and Linux and it seems to work fine.

kitty --config=NONE -o 'font_family Iosevka Slab' -o 'font_features  Iosevka-Slab -calt +JSPT'

When I type ===, it will be rendered as shown in the screenshot above.

You should note that for fonts with different styles, you need to turn them on one by one. For example, Iosevka-Slab-Bold.

font_features Iosevka-Slab -calt +JSPT
font_features Iosevka-Slab-Italic -calt +JSPT
font_features Iosevka-Slab-Bold -calt +JSPT
font_features Iosevka-Slab-Bold-Italic -calt +JSPT

[benfrain]

Just checking ;) Which screenshot?

Weird. Wonder if my build of Iosevka doesn't have that build?? I got the one from brew install --cask font-iosevka-slab but perhaps that doesn't have those glyphs by default?

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https://github.com/be5invis/Iosevka/blob/v11.2.2/doc/language-specific-ligation-sets.md

The same style as the official screenshot, with three horizontal lines of equals.

I downloaded Iosevka v11.2.2 ttc release package (multiple ttc files, e.g. sgr-iosevka-ss14-regular.ttc, ...), and installed it manually. I guess homebrew is using the official release package.

I also confirmed the font PostScript names by kitty +list-fonts --psnames. You should note that for fonts with different font weights, you need to turn them on one by one. For example, Iosevka-SS14-Bold.

[benfrain]

Wait, I know the font is fine because the same font and setting looks right in VSCode!

Here is my Kitty config. I'm using kitty 0.23.1 on macOS 11.6.2:

font_family      Iosevka Slab
bold_font        Iosevka Slab Bold
italic_font    Iosevka Slab Italic
bold_italic_font Iosevka Slab Bold Italic
font_features   Iosevka-Slab -calt +JSPT

I have checked the postscript name and that is definitely correct. Are you saying I need to do something more here?

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I tested kitty version 0.23.1 under macOS 12.1.

1. Install the fonts according to the files used by Homebrew.
   https://github.com/Homebrew/homebrew-cask-fonts/blob/639979a5eb1b42f8e9938ce12dcfec0bd69e4c4d/Casks/font-iosevka-slab.rb
   download: https://github.com/be5invis/Iosevka/releases/download/v11.2.2/ttc-iosevka-slab-11.2.2.zip
   extract, double click and install:
   iosevka-slab-regular.ttc
   iosevka-slab-bold.ttc

2. Download and open kitty-0.23.1.dmg

3. Run kitty 0.23.1

kitty +list-fonts --psnames

Iosevka Slab
    Iosevka Slab Extended (Iosevka-Slab-Extended)
    Iosevka Slab Extended Italic (Iosevka-Slab-Extended-Italic)
    Iosevka Slab Extended Oblique (Iosevka-Slab-Extended-Oblique)
    Iosevka Slab Italic (Iosevka-Slab-Italic)
    Iosevka Slab Oblique (Iosevka-Slab-Oblique)
    Iosevka Slab Regular (Iosevka-Slab)

/Volumes/kitty-0.23.1/kitty.app/Contents/MacOS/kitty --config=NONE \
  -o remember_window_size=no \
  -o initial_window_height=24c \
  -o initial_window_width=80c \
  -o font_size=24 \
  -o 'font_family Iosevka Slab' \
  -o 'bold_font Iosevka Slab Bold' \
  -o 'italic_font Iosevka Slab Italic' \
  -o 'bold_italic_font Iosevka Slab Bold Italic' \
  -o 'font_features Iosevka-Slab -calt +JSPT' \
  --debug-font-fallback \
  sh -c 'printf ===;read'

Preloaded font faces:
normal face: $HOME/Library/Fonts/iosevka-slab-regular.ttc      
bold face: $HOME/Library/Fonts/iosevka-slab-bold.ttc      
italic face: $HOME/Library/Fonts/iosevka-slab-regular.ttc      
bi face: $HOME/Library/Fonts/iosevka-slab-bold.ttc

The three equal signs are rendered as three connected horizontal lines.

I can't reproduce the issue and can't think of anything else that would cause it, other than the font or system environment, or edge compatibility issue.

[benfrain]

Thanks for doing that, this is odd for sure.

❯ kitty --config=NONE -o 'font_size 21' -o 'font_family Iosevka Slab' -o 'font_features Iosevka-Slab -calt +JSPT' --debug-font-fallback
[355 17:48:21.928077] Preloaded font faces:
[355 17:48:21.928103] normal face: /Users/benfrain/Library/Fonts/iosevka-slab-regular.ttc
[355 17:48:21.928113] bold face: /Users/benfrain/Library/Fonts/iosevka-slab-semibold.ttc
[355 17:48:21.928122] italic face: /Users/benfrain/Library/Fonts/iosevka-slab-regular.ttc
[355 17:48:21.928130] bi face: /Users/benfrain/Library/Fonts/iosevka-slab-semibold.ttc

Still only get the two lines in kitty. Again, thanks for taking the time to test fully. If I manage to figure it out I'll update here.

[benfrain]

Well some progress in figuring this out. Seems to be related to neovim, or how I have it configured. If I run the command you gave above using printf then I see the 3 line glyph. But still when I write it in neovim js file I see double.

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Have you tried nvim -u NONE?

I confirmed that with kitty nightly version and neovim 0.6.0, three equals rendered fine.

font_features Iosevka-Slab -calt +JSPT
font_features Iosevka-Slab-Italic -calt +JSPT
font_features Iosevka-Slab-Bold -calt +JSPT
font_features Iosevka-Slab-Bold-Italic -calt +JSPT

[kovidgoyal]

Use --debug-font-fallback and open a file with just === in it and see what fonts are being used. My guess would be either that neovim is using a bold/italic variant or that it is not output the actual === to the terminal.

[benfrain]

So, this is odd. If I start a new file, type in === then I get expected three lines. If I save the file (just with three equals in) as a js file, it changes the display of it to two line variant. Vid attached

wtf.mov

Obviously at this point it seems obvious this is not to do with Kitty!

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I noticed that when you save it as a js file, the syntax for the three equal signs seems to be in BOLD. So did you configure Iosevka-Slab-Bold? I mentioned this earlier.

You should note that for fonts with different font weights (EDIT: style, italic or bold), you need to turn them on one by one. For example, Iosevka-SS14-Bold.

[benfrain]

aha, sorry, I had misunderstood. Let me try that now...

Yep, that's all it was! Sorry!

Thanks for all the assitance. Now marked your edited post above as the answer for future travellers