Allow both relative and absolute module paths.

[Fuuzetsu]

This allows for the following to work:

[nix-shell:~/programming/easyspec]$ stack build --nix easyspec && stack exec --nix -- easyspec discover ../../../../tmp/MySort.hs MySort.mySort
mySort xs <= xs = y <= y
mySort (mySort xs) = mySort xs

[nix-shell:~/programming/easyspec]$ stack build --nix easyspec && stack exec --nix -- easyspec discover /tmp/MySort.hs MySort.mySort
mySort xs <= xs = y <= y
mySort (mySort xs) = mySort xs

I may or may not have broken stuff in easyspec-evaluate: I mostly
just changed the types to line up there. If there's a good way to test
that, I can do it.

Not only can we use absolute paths now, relative paths of the
src/Foo/Bar.hs sort are fixed: we ask GHC to give us the module name
instead of trying to guess it. In general it's not possible to guess a
module name from the file path with any accuracy.

[Fuuzetsu]

Also this is without zifter; I tried to run it but

diff --git a/zift.hs b/zift.hs
index 4793fe2..9b844d8 100755
--- a/zift.hs
+++ b/zift.hs
@@ -1,5 +1,7 @@
 #!/usr/bin/env stack
 {- stack
+    --nix
+    --system-ghc
     --install-ghc
     runghc
     --package zifter

[nix-shell:~/programming/easyspec]$ /tmp/zifter/zift.hs run
Completed 15 action(s).
PREPROCESSOR STARTING
  RECURSIVE PREPROCESSING STARTING/bin/sh: cabal: command not found
 FROM /home/shana/progr/bin/sh: wget: command not found
amming/easyspec/

cabal /bin/sh: /home/shana/.local/bin/hindent: No such file or directory
--version failed with exit code 127

So I just gave up.

[Fuuzetsu]

Blocked on #2 I guess.

[NorfairKing]

You could already specify paths from any directiry with --base-dir. Otherwise imports don't work anymore, right?
Do the easyspec tests still pass? Travis doesn't run them, if I recall correctly, for reasons related to quick iteration.

[Fuuzetsu]

I have not tried with imports nor didn't try running the tests. I will try in coming days. I don't see why imports should become broken as far as GHC is concerned at least: it should be able to find modules just by walking the hierarchy fine.

[NorfairKing]

it should be able to find modules just by walking the hierarchy fine.

Okay, but how do you know the difference between module MySort in a Tmp directory and module Tmp.MySort in your new system?

[Fuuzetsu]

GHC tells us the module name. It's either in the file or Main.

[NorfairKing]

GHC tells us the module name. It's either in the file or Main.

Genius! I'll take a closer look at this PR when we've chosen a license (and only if you're okay with it) and try to fix this.