[Haskell-cafe] Using stack outside the project box

Galaxy Being borgauf at gmail.com
Sun Jun 6 19:45:52 UTC 2021

As a beginner, I was told to use stack. And I seemed to get something
Haskell installed initially on my Ubuntu 21.04. But stack seems to be
geared toward projects and compiling executables with ghc, and not a global
ghci REPL-based way. I'm using Emacs org mode "Babel" which allows for a
very nice "literate" programming in tandem with a running REPL in many
REPL-friendly languages, e.g., here are code blocks in an org-mode file

#+begin_src haskell :results silent :exports code
data Peano = Zero | Succ Peano deriving (Show)

#+begin_src haskell :results silent :exports code
myThree = Succ (Succ (Succ Zero))

#+begin_src haskell :results verbatim :exports both

: Succ (Succ (Succ Zero))

I simply hit Evaluate (Ctr-C Ctr-C) and the evaluation is handled by a
running ghci REPL started up in another Emacs buffer. Supposedly, a
haskell-mode and a specific Babel ob-haskell package are working together
to enable this. And so it works okay, once quirks (must enclose multi-lined
code in :{..:} and every REPL session seems to need a :set +m as well). I'm
really quite happy with this way of doing things and have resisted the
whole monolithic 1) create project in a directory, 2) put code into .hs
file, 3) compile with ghc.

But what I'm constantly having problems with is getting additional packages
beyond the Prelude basics. My org files are in various directories, but I
want (like most languages offer) to simply interact with that language on a
global level wherever I am, whatever files and directories and Haskell code
I'm working on. Sometimes doing an import works; often enough not. Then I
have to do something with stack -- hopefully globally . . . and there the
confusion and inconsistencies begin. Lately I can't seem to get Safe
installed. And all docs about editing some yaml stuff get me lost in the
weeds quickly. What yaml where for my "global" situation?

If you simply say to me, Don't try to work outside of the project--hs
files--compile to executable framework I'll say okay, then have to decide
whether I want to stay within the org-mode world or leave Haskell for an
org-mode friendlier language. And no, lhs and jupyter are primitive
compared to org-mode literate programming. Both are a step backwards.

Any help on working outside the project box with stack, e.g., how to
install and use packages (and even how to update/upgrade ghc and ghci would
be a start!).

Lawrence Bottorff
Grand Marais, MN, USA
borgauf at gmail.com
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