If you manually set HSCOLOUR_SRCS=YES then the build will fail if
HsColour wasn't found.
#
XMLDocWays=
-# Should we build haddock docs?
-HADDOCK_DOCS = YES
-# And HsColour the sources?
-HSCOLOUR_SRCS = YES
-
# Should we build latex docs?
LATEX_DOCS = NO
#
GHC_ALEX_OPTS = -g
+# Should we build haddock docs?
+HADDOCK_DOCS = YES
+# And HsColour the sources?
+ifeq "$(HSCOLOUR)" ""
+HSCOLOUR_SRCS = NO
+else
+HSCOLOUR_SRCS = YES
+endif
+
#
# Options for compiling in different `ways'.
#