From 6ac6655c9f644d34160b0f838cf6558d66e9d39c Mon Sep 17 00:00:00 2001
From: Mikhail Timofeev <48208649+miketimofeev@users.noreply.github.com>
Date: Fri, 29 May 2020 14:38:59 +0300
Subject: [PATCH] more readable script (#956)

---
 images/linux/scripts/installers/haskell.sh | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/images/linux/scripts/installers/haskell.sh b/images/linux/scripts/installers/haskell.sh
index 1d4dd02da..32e4fc4dd 100644
--- a/images/linux/scripts/installers/haskell.sh
+++ b/images/linux/scripts/installers/haskell.sh
@@ -13,14 +13,20 @@ apt-get install -y software-properties-common
 add-apt-repository -y ppa:hvr/ghc
 apt-get update
 
-# Get 3 latest Haskell versions and latest Cabal version
-ghcVersions=$(apt-cache search "^ghc-" | grep -Po '(\d*\.){2}\d*' | awk 'BEGIN {FS=OFS=SUBSEP="."}{if (arr[$1,$2] < $3) arr[$1,$2] = $3} END {for (i in arr) print i,arr[i]}' | sort --version-sort | tail -3)
-cabalVersion=$(apt-cache search cabal-install-[0-9] | grep -Po '\d*\.\d*' | sort --unique --version-sort | tail -1)
+# Get 3 latest Haskell Major.Minor versions
+allGhcVersions=$(apt-cache search "^ghc-" | grep -Po '(\d*\.){2}\d*' | sort --unique --version-sort)
+ghcMajorMinorVersions=$(echo "$allGhcVersions" | cut -d "." -f 1,2 | sort --unique --version-sort | tail -3)
 
-for version in $ghcVersions; do
-    apt-get install -y ghc-$version
+for version in $ghcMajorMinorVersions; do
+    # Get latest patch version for given Major.Minor one (ex. 8.6.5 for 8.6) and install it
+    exactVersion=$(echo "$allGhcVersions" | grep $version | sort --unique --version-sort | tail -1)
+    apt-get install -y ghc-$exactVersion
+    ghcInstalledVersions+=("$exactVersion")
 done
 
+# Get latest cabal version
+cabalVersion=$(apt-cache search cabal-install-[0-9] | grep -Po '\d*\.\d*' | sort --unique --version-sort | tail -1)
+
 apt-get install -y cabal-install-$cabalVersion
 
 # Install the latest stable release of haskell stack
@@ -50,7 +56,7 @@ fi
 # Document what was added to the image
 echo "Lastly, documenting what we added to the metadata file"
 DocumentInstalledItem "Haskell Cabal ($(/opt/cabal/$cabalVersion/bin/cabal --version))"
-for version in $ghcVersions; do
+for version in ${ghcInstalledVersions[@]}; do
     DocumentInstalledItem "GHC ($(/opt/ghc/$version/bin/ghc --version))"
 done
 DocumentInstalledItem "Haskell Stack ($(stack --version))"