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+
+* haskell-ts-mode
+
+A haskell mode that uses treesitter.
+
+* Screenshot
+
+[[./ss.png]]
+
+The above screenshot is indented coloured using haskell-ts-mode, with
+prettify-symbols-mode enabled.
+
+* Usage
+
+=C-c C-r= to open REPL
+=C-c C-c= to send code to repl
+=C-M-q=   Indent paragraph
+
+* Features
+an overview of the features are:
+- Syntax highliting
+- Indentation
+- Imenu support
+- REPL (C-c r in the mode to run)
+- Prettify symbols mode support
+
+* Comparasion with haskell-mode
+The more interesting features are:
+- Logical syntax highlighting:
+  - Only arguments that can be used in functions are highlighted, eg
+    in `f (_:(a:[])) only 'a' is highlighted, as it is the only
+    variable that is captured that can be used in body of function
+  - The return type of a function is highlighted
+  - All new variabels are(or should be) highlighted, this includes
+    generators, lambda args.
+  - highlighting the '=' operaotr in guarded matches correctly, this
+    would be stupidly hard in regexp based syntax
+- Unlike haskell-mode, quasi quotes are understood and do not confuse
+  the mode, thanks to treesitter
+- Predictable (but less powerful) indentation: haskell-mode's
+  indentation works in a cyclical way, it cycles through where you
+  might want indentation.  haskell-ts-mode, meanwhile relies on you to
+  set the concrete syntax tree changing whitespace.
+- More perfomant, this is especially seen in longer files
+- Much much less code, haskell mode has accumlated 30,000 lines of
+  features to do with all things haskell related, this mode just keeps
+  the scope to basic major mode stuff, and leaves other stuff for
+  external packages.
+
+* Motivation
+  
+haskell-mode contains nearly 30k lines of code, and is
+about 30 years old.  Therefore, a lot of stuff emacs has gained the
+ability to do in those years, haskell-mode already has implemented
+them.
+
+In 2018, a mode called haskell-tng-mode was made to solve some of
+these problems. However because of haskell's syntax, it too became
+very complex and required a web of dependencies.
+
+Both these modes ended up practically parsing haskells syntax to
+implement indentation, so I thought why not use tree sitter?
+
+* Installation
+
+The package is avaiable on elpa, you can install it using:
+M-x package-install RET haskell-ts-mode RET
+
+#+begin_src elisp
+(add-to-list 'load-path "path/to/haskell-ts-mode")
+(require 'haskell-ts-mode)
+#+end_src
+
+* Customization
+
+If colour is too much or too less for you, adjust
+treesit-font-lock-level accordingly.
+
+If you want to highlight signature declarations (disabled by default),
+add the following to your init file:
+#+begin_src emacs-lisp
+(setq haskell-ts-highlight-signature t)
+#+end_src
+
+** how to disable haskell-ts-mode indentation
+
+#+begin_src emacs-lisp
+(setq haskell-ts-use-indent nil)
+#+end_src
+
+** Pretify symbols mode
+prettify symbols mode can be used to replace common symbols with
+unicode alternatives.
+
+#+begin_src emacs-lisp
+(add-hook 'haskell-ts-mode 'prettify-symbols-mode)
+#+end_src
+
+** Adjusting font lock level
+set haskell-ts-font-lock-level accordingly.
+
+** Language server
+
+haskell-ts-mode is compatiable with lsp-haskell.
+
+To enable eglot support, use the following code in your init.el:
+#+begin_src emacs-lisp
+(with-eval-after-load 'eglot (haskell-ts-setup-eglot))
+#+end_src
+
+* TODO and limitations
+- Imenu support for functions with multiple definitions
+
+Limitations: _Proper indenting of multiline signatures_: the
+treesitter grammer does not flatten the signautes, rather leaves them
+to the standard infix interpretatoin. This makes indentation hard, as
+it will mean the only way to check if the the signature node is an
+ancestor of node at point is to perfom a recursive ascent, which is
+horrible for perfomance.