Eev and Haskell

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Eev and Haskell

I am trying to learn Haskell,
and trying to make it easy to use from REPLs with eepitch.
All the "notes" links below point to "executable notes".

I am using a GHC installed with GHCup (notes),
with cabal-install (disambiguation) from Debian (notes),
and with Hoogle installed from Hackage (notes, notes).
Debian has packages for the report and the tutorial for Haskell98 (notes),
and I saw that I can use eev-rstdoc.el to point to them, like this:

-- (find-h98doc "index")
-- (find-h98tdoc "index")
-- (find-ghcugdoc "index")

1. `find-cabal-links'

One thing that I found very annoying about Haskell is that after installing a package with cabal-install I had to use commands like this

ghc-pkg --package-db=/home/edrx/.cabal/store/ghc-8.8.4/package.db describe hoogle

to get information on an installed package; I don't know how to set a default value for "--package-db" yet, so I wrote this shell script as a workaround: ~/bin/eev-cabal. When I run this sexp (a 5-minute hack!),

# (find-cabal-links "hoogle")

it displays a temporary buffer like the one at the upper right in the screenshot below (click to enlarge it!), that contains several elisp hyperlinks that invoke eev-cabal with different arguments,

After those hyperlinks it shows an eepitch block for installing that package, and a link like this -

# (find-cabal-unpack "hoogle")

that only works correctly on installed packages, and that displays a temporary buffer like the one at the lower right part of the screenshot, that unpacks the source code of that package into a directory with a short name, and produces a code-c-d for it. The code in Lisp for find-cabal-links and find-cabal-unpack is quite simple, but I was only able to write eev-cabal after getting a lot of help in the #haskell IRC channel. =/

2. `find-ghc-links'

Here is another 5-minute hack that I am using a lot: find-ghc-links. When I type `M-x find-ghc-links' or `M-x ghl' it displays a temporary buffer like this (click to enlarge!),

with some useful links on the word around point. It works for both functions and names of modules - some of the links are only meaningful when the argument is the name of a function, and some only when it is the name of a module.