improve ghc-info.sh with a show mode

ghc-info.sh

@@ -1,8 +1,12 @@
 #!/bin/sh
 
-[ $# -lt 2 ] && echo "Usage: $(basename "$0") GHCVERSION INFOFIELD"
+[ $# -lt 1 ] && echo "Usage: $(basename "$0") GHCVERSION INFOFIELD" && exit 1
 
-GHCVER=$1
-FIELD=$2
+GHCVER="$1"
+FIELD="$2"
 
-/usr/bin/ghc-${GHCVER} --info | grep \"$FIELD\" | sed -e 's/.*","\(.*\)")/\1/'
+if [ -z "$FIELD" ]; then
+    /usr/bin/ghc-${GHCVER} --info | sed -e 's/.*(\(".*"\),\(".*"\).*/\1: \2/' -e '/]/d'
+else
+    /usr/bin/ghc-${GHCVER} --info | grep \""$FIELD"\" | sed -e 's/.*","\(.*\)")/\1/'
+fi