Merge request #731 default.nix: switch to the GHC 8.10.1, now executable gets build

Switching Nix dev env and its CI to GHC 8.10.

To avoid contribution loop problems, since we pin Nixpkgs in default.nix - it is logical by default CI to follow the supported way of building.

The downsides are:
  * Maintainer would need to solve Nix issues by himself, when wants to update the Nixpkgs revision, or play a wait and pick rev game with Nixpkgs.
  * On the rev update, the `Nix-shell & Hoogle` CI build needs to rebuild the whole Haskell stack from the bottom up, so the rev update process takes a lot of wait time (hours), and also should be done from the repo internal branch to save the already built parts of the stack during rev testing.

Also one CI build was not terminating, so switched to the new rev.

.github/workflows/Optional-Nix-dev-env-macOS.yml

@@ -13,14 +13,14 @@ on:
 
 
 env:
-  rev: "nixos-unstable"
+  # rev: "nixos-unstable"         #  2020-09-29: NOTE: HNix default.nix currently pins the rev
   cachixAccount: "hnix"
   CACHIX_SIGNING_KEY: ${{ secrets.CACHIX_SIGNING_KEY }}
 
 
 jobs:
   build10:
-    name: "NixOS-unstable, default GHC (8.8)"
+    name: "Default GHC (8.8)"
     runs-on: macos-latest
     continue-on-error: true
     steps:

.github/workflows/Optional-Nix-dev-env-main.yml

@@ -22,7 +22,7 @@ env:
   ### and the other part of keys explained in `build.sh`, since those address external procedures aound the builds.
   ### Additional documentation is in Nixpkgs Haskell.lib: https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/haskell-modules/lib.nix
   ###
-  rev: "nixos-unstable"
+  # rev: "nixos-unstable"         #  2020-09-29: NOTE: HNix default.nix currently pins the rev
   cachixAccount: "hnix"
   CACHIX_SIGNING_KEY: ${{ secrets.CACHIX_SIGNING_KEY }}
   allowInconsistentDependencies: "false"
@@ -56,9 +56,8 @@ env:
 
 jobs:
 
-  # NOTE: Basic example
   build10:
-    name: "NixOS-unstable channel, strict build, default GHC (8.8)"
+    name: "Default Nixpkgs GHC (8.8), strict build"
     runs-on: ubuntu-latest
     #  2020-08-01: NOTE: Due to Nixpkgs brittleness to not block project development Nixpkgs made optional, see commit message for more info
     continue-on-error: true
@@ -76,13 +75,13 @@ jobs:
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
     - name: Determined Nix-build
       env:
-        rev: "nixos-unstable"
+        compiler: "default"
         buildStrictly: "true"
       run: ./build.sh
 
 
   build20:
-    name: "Quality build, SDist, Optimizations, Benchmark, Haddock, Completions, GHC 8.10.1"
+    name: "GHC 8.10.1, quality build, SDist, Optimizations, Benchmark, Haddock, Completions"
     runs-on: ubuntu-latest
     continue-on-error: true
     steps:
@@ -99,7 +98,6 @@ jobs:
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
     - name: Determined Nix-build
       env:
-        rev: "nixos-unstable"
         compiler: "ghc8101"
         buildFromSdist: "true"
         linkWithGold: "true"

default.nix

@@ -1,7 +1,7 @@
 {
-# Default GHC for Nixpkgs by default, for current default and explicitly supported GHCs https://search.nixos.org/packages?query=ghc&from=0&size=500&channel=unstable, Nixpkgs implicitly supports older minor versions also, until the configuration departs from compatibility with them.
+# For current default and explicitly supported GHCs https://search.nixos.org/packages?query=ghc&from=0&size=500&channel=unstable, Nixpkgs implicitly supports older minor versions also, until the configuration departs from compatibility with them.
 # Compiler in a form ghc8101 <- GHC 8.10.1, just remove spaces and dots
-  compiler    ? "default"
+  compiler    ? "ghc8101"
 
 # Deafult.nix is a unit package abstraciton that allows to abstract over packages even in monorepos:
 # Example: pass --arg cabalName --arg packageRoot "./subprojectDir", or map default.nix over a list of tiples for subprojects.
@@ -91,7 +91,7 @@
 #   , nixos-20.03  # Last stable release, gets almost no updates to recipes, gets only required backports
 #   ...
 #   }
-, rev ? "daaa0e33505082716beb52efefe3064f0332b521"
+, rev ? "0cfe5377e8993052f9b0dd56d058f8008af45bd9"
 
 , pkgs ?
     if builtins.compareVersions builtins.nixVersion "2.0" < 0