[ actions ] Relaxing build constraints (#8)

We are now building the project with all of the versions of ghc made available
to us by https://github.com/actions/setup-haskell

To make the builds as fast as possible, we are caching `.cabal` and `.ghc`
for each one of the versions. So far that should take around 1G (5*200M)
which is way below the 5G allowance we have.

.github/workflows/haskell.yml

@@ -6,21 +6,54 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        ghc: ['8.8.1', '8.6.5', '8.4.4', '8.2.2', '8.0.2']
+        include:
+          - ghc: '8.8.1'
+            cabal: '3.0'
+          - ghc: '8.6.5'
+            cabal: '3.0'
+          - ghc: '8.4.4'
+            cabal: '2.2'
+          - ghc: '8.2.2'
+            cabal: '2.0'
+          - ghc: '8.0.2'
+            cabal: '2.0'
 
     steps:
     - uses: actions/checkout@v2
+
     - uses: actions/setup-haskell@v1
       with:
-        ghc-version: '8.6.5'
-        cabal-version: '3.0'
+        ghc-version: ${{ matrix.ghc }}
+        cabal-version: ${{ matrix.cabal }}
+
+    - uses: actions/cache@v1
+      name: Cache ~/.cabal/
+      with:
+        path: ~/.cabal/
+        key: ${{ runner.os }}-ghc-${{ matrix.ghc }}-cabal-${{ matrix.cabal }}-cabal
+
+    - uses: actions/cache@v1
+      name: Cache ~/.ghc/
+      with:
+        path: ~/.ghc/
+        key: ${{ runner.os }}-ghc-${{ matrix.ghc }}-cabal-${{ matrix.cabal }}-ghc
+
+    - name: Remove existing mary binary
+      run: rm -f ~/.cabal/bin/mary
+
     - name: Install dependencies
       run: |
         cabal update
         cabal install --only-dependencies
+
     - name: Build
       run: |
         cabal configure --enable-tests
         cabal build
+
 # no tests yet
 #    - name: Run tests
 #      run: cabal test

mary.cabal

@@ -18,6 +18,12 @@ synopsis:            Content delivery system for CIS
 -- A longer description of the package.
 -- description:
 
+tested-with:        GHC == 8.0.2
+                    GHC == 8.2.2
+                    GHC == 8.4.4
+                    GHC == 8.6.5
+                    GHC == 8.8.1
+
 -- URL for the project homepage or repository.
 homepage:            https://github.com/msp-strath/Mary
 
@@ -68,13 +74,13 @@ executable mary
 --  other-extensions:
 
   -- Other library packages from which modules are imported.
-  build-depends:       base >=4.12 && <4.13
+  build-depends:       attoparsec >=0.13 && <0.14
+                     , base >=4.9.1.0 && <4.14
                      , containers >=0.6 && <0.7
-                     , attoparsec >=0.13 && <0.14
-                     , text >=1.2 && <1.3
-                     , prettyprinter >=1.6 && <1.7
-                     , pandoc-types >=1.19 && <1.21
                      , mtl >=2 && <3
+                     , pandoc-types >=1.19 && <1.21
+                     , prettyprinter >=1.6 && <1.7
+                     , text >=1.2 && <1.3
 
   -- Directories containing source files.
   hs-source-dirs:      src
@@ -85,12 +91,12 @@ executable mary
     -- LANGUAGE extensions used by modules in this package.
   default-extensions:  DeriveTraversable
                      , LambdaCase
+                     , OverloadedStrings
                      , PatternSynonyms
                      , TupleSections
-                     , OverloadedStrings
 
   ghc-options:         -Wincomplete-patterns
-                       -Woverlapping-patterns
                        -Wmissing-signatures
+                       -Woverlapping-patterns
                        -Wtabs
                        -fwarn-unused-imports

src/Shonkier/Examples.hs

@@ -1,6 +1,7 @@
 module Shonkier.Examples where
 
 import Data.Map (singleton)
+import Data.Semigroup ((<>)) -- needed for ghc versions <= 8.2.2
 
 import Data.Bwd
 import Shonkier.Syntax

src/Shonkier/Pretty.hs

@@ -9,6 +9,7 @@ import Shonkier.Semantics
 import Data.Char
 import Data.Foldable
 import Data.Ratio
+import Data.Semigroup ((<>)) -- needed for ghc versions <= 8.2.2
 import qualified Data.Text as T
 import Data.Text.Prettyprint.Doc
 

src/Shonkier/Semantics.hs

@@ -10,6 +10,7 @@ import Data.Either
 import Data.Map (Map, singleton, (!?))
 import Data.List (sortBy, groupBy, nub)
 import Data.Maybe (fromMaybe)
+import Data.Semigroup ((<>)) -- needed for ghc versions <= 8.2.2
 import Data.Text (Text)
 import qualified Data.Text as T
 

src/mary.hs

@@ -2,17 +2,21 @@
 
 module Main where
 
-import Text.Pandoc.Definition
-import Text.Pandoc.Walk
-import Text.Pandoc.JSON
+import Control.Monad.Writer (Writer, runWriter, tell)
+
+import Data.Attoparsec.Text
+import Data.Semigroup ((<>)) -- needed for ghc versions <= 8.2.2
 import qualified Data.Text as T
 import Data.Text.IO as TIO
-import System.Environment
-import Control.Monad.Writer
-import Data.Attoparsec.Text
 import Data.Text.Prettyprint.Doc
 import Data.Text.Prettyprint.Doc.Render.Text
 
+import System.Environment
+
+import Text.Pandoc.Definition
+import Text.Pandoc.Walk
+import Text.Pandoc.JSON
+
 import Data.Bwd
 import Shonkier.Examples
 import Shonkier.Parser