don"t explode on unknown extension

1 files changed, 7 insertions, 0 deletions

diff --git a/prose.lua b/prose.lua
index 99e298a..b064826 100644
--- a/prose.lua
+++ b/prose.lua
@@ -93,5 +93,12 @@ extensions.meta = function(S,text)
 	local fn = assert(load(string.format("return {%s}", text),"meta", "t"))
 	S.meta = fn()
 end
+setmetatable(extensions, {__index = function(t, k)
+	return function(S, text)
+		io.stderr:write("warning: unknown extension "..k.."\n")
+		return text
+	end
+end})
 
 return prose
+