2 files changed, 19 insertions, 1 deletions
diff --git a/isabat b/isabat
index 12efd1d..6b797ee 100755
--- a/isabat
+++ b/isabat
@@ -1,12 +1,28 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+if ! type bat > /dev/null
+then
+    echo "Error: \$PATH appears to lack bat. Please install it to use isabat."
+    exit 1
+fi
+
+if [ $( bat --list-languages | grep Isabelle | wc -l) -eq 0 ]
+then
+    echo "Error: your installation of \`bat\` lacks a syntax highlighter for Isabelle."
+    echo ""
+    echo "Please place the isabelle.sublime-syntax file in $( bat --config-dir)/syntaxes,"
+    echo "then run \`bat cache --build\` to make it available to bat."
+    exit 1
+fi
+
+
 if [ $# -eq 0 ]
 then
     echo "isabat: pretty-print isabelle theories on a terminal using bat."
     echo ""
     echo "please provide a .thy file to display."
-    exit
+    exit 1
 fi
 
 cat "$1" | isabelle2unicode | bat --file-name "$1" --theme TwoDark
diff --git a/isabat.nix b/isabat.nix
index 7fc05f2..de6ce6f 100644
--- a/isabat.nix
+++ b/isabat.nix
@@ -17,6 +17,8 @@ stdenv.mkDerivation {
     cp $src isabat
     substituteInPlace isabat \
       --replace isabelle2unicode "${isabelle-unicode}/bin/isabelle2unicode"
+    substituteInPlace isabat \
+      --replace " bat " " ${pkgs.bat}/bin/bat "
     cp isabat $out
   '';
 }