When comparing Hasklig vs Hack, the Slant community recommends Hack for most people. In the question“What are the best programming fonts?” Hack is ranked 7th while Hasklig is ranked 28th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great for Haskell
Pro Has a heavier appearance than Fira Code or Monoid
Pro Completely free and open source
Freely available via GitHub, therefore can be modified and improved by anyone.
Pro Has many variants such as Italic, Bold Italic, Light, Semibold, etc., etc
Pro Very readable
Pro Libre webfonts are available in svg, eot, ttf, woff, and woff2 formats
Hack is free for unlimited commercial and non-commercial use. The webfonts are hinted (TrueType instruction set) to optimize display on the screen and are built into all commonly used web font formats with each new release. They include the complete release character set and smaller (filesize) basic Latin subset releases. They are available in the build directory of the repository.
Pro Fixes many readability issues in Vera/DejaVu
The tilde symbol ('~'), comma (',') and semicolon (';') glyphs have been modified to be more readable at small sizes and/or on non-HD displays. In addition, the underscore symbol ('_') has been slightly lifted for alignment with surrounding characters.
Pro Avaliable in many GNU/Linux distro package manager
Including Debian/Ubuntu (fonts-hack), Fedora (font-hack-ttf), OpenSUSE (hack-fonts), Arch (ttf-hack) and probably many more. Much nicer than having to manually install/update
Pro Free/Open license
Pro Renders accurately on Windows on all font sizes
Pro Based on the tried and tested Bitstream Vera Sans Mono
The fonts are in the Vera Sans Mono lineage with a significant expansion of the character set (which includes Cyrillic and modern Greek character sets), new glyph shapes and modifications of the original glyph shapes, as well as improvements in metrics and hinting/TT instructions to make it more legible at small text sizes used for source code.
The changelog is available here.
Pro Powerline glyph patch is included
The regular set is patched with Powerline glyphs by default. There is no need to patch the font to use it in Powerline environments.
Pro Source code is released in UFO format
UFO source format is widely supported by all modern font editors if you would like to modify the typeface.
Cons
Con Lacks !=
Some coding fonts with ligatures, like Fira Code, turn != into ≠, but Hasklig does not. The reason for this is that Hasklig was designed for Haskell code, and so turns /= into ≠ instead.
Con Some Ligatures like -<< don't look that good.
Con Has a heavier appearance than Fira Code or Monoid
Con No support for many editors, including emacs
Unfortunately, not supporting emacs is the number one reason I don't use this font all the time.
Con Very cute but not WYSIWYG
You want to see exactly what you've typed, not have your brain have to do a little dance every time you see one of these artifacts.
Con No ligatures in the default font
Although patched versions with ligatures do exist - see here.
Con Sometimes difficult to distinguish lowercase "i" (eye) and lowercase "l" (ell)
When using a higher resolution monitor and a smaller font size, the lowercase "i" (eye) and lowercase "l" (ell) are very difficult to distinguish. The space between the dot and the remainder of the letter seems to somehow disappear, thereby making it look like a solid line, similar to the lowercase "l" (ell).
Con Too similar to DejaVu
See this gif comparison between the two fonts.