Index: cli.lua
==================================================================
--- cli.lua
+++ cli.lua
@@ -4,29 +4,10 @@
 local default_mode = {
 	['render:format'] = 'html';
 	['html:gen-styles'] = true;
 }
 
-local function
-kmap(fn, list)
-	local new = {}
-	for k, v in pairs(list) do
-		local nk,nv = fn(k,v)
-		new[nk or k] = nv or v
-	end
-	return new
-end
-
-local function
-kfilter(list, fn)
-	local new = {}
-	for k, v in pairs(list) do
-		if fn(k,v) then new[k] = v end
-	end
-	return new
-end
-
 local function
 main(input, output, log, mode, suggestions, vars)
 	local doc = ct.parse(input.stream, input.src, mode)
 	input.stream:close()
 	if mode['parse:show-tree'] then
@@ -45,13 +26,13 @@
 	if mode['render:format'] == 'none' then return 0 end
 	if not ct.render[mode['render:format']] then
 		ct.exns.unimpl('output format “%s” unsupported', mode['render:format']):throw()
 	end
 	
-	local render_opts = kmap(function(k,v)
+	local render_opts = ss.kmap(function(k,v)
 		return k:sub(2+#mode['render:format'])
-	end, kfilter(mode, function(m)
+	end, ss.kfilter(mode, function(m)
 		return ss.str.begins(m, mode['render:format']..':')
 	end))
 
 	doc.vars = vars
 	
@@ -138,10 +119,33 @@
 		['mode-clear'] = function(key) mode[checkmodekey(key)] = false end;
 
 		['mode-weak'] = function(key,value) suggestions[checkmodekey(key)] = value end;
 		['mode-set-weak'] = function(key) suggestions[checkmodekey(key)] = true end;
 		['mode-clear-weak'] = function(key) suggestions[checkmodekey(key)] = false end;
+
+		['version'] = function()
+			outp:write(ct.info:about())
+			if next(ct.ext.loaded) then
+				outp:write('\nactive extensions:\n')
+				for k,v in pairs(ct.ext.loaded) do
+					outp:write(string.format(' * %s', v.id ..
+						(v.version and (' ' .. v.version:string()) or '')))
+					if v.desc then
+						outp:write(string.format(': %s', v.desc))
+						if v.contributors then
+							outp:write(string.format(' [%s]', table.concat(
+								ss.map(function(ctr)
+									return ctr.name or ctr.handle
+								end, v.contributors), ', ')))
+						end
+					else
+						outp:write'\n'
+					end
+				end
+			end
+			os.exit(0)
+		end
 	}
 
 	local args = {}
 	local keepParsing = true
 	do local i = 1 while i <= #arg do local v = arg[i]
@@ -151,19 +155,21 @@
 			end
 			local nargs = optnparams(longopt)
 
 			if nargs > 1 then
 				if i + nargs > #arg then
-					ct.exns.cli('not enough arguments for switch --%s (%u expected)', longopt, nargs):throw()
+					ct.exns.cli('not enough arguments for switch --%s (%s expected)', longopt, nargs):throw()
 				end
 				local nt = {}
 				for j = i+1, i+nargs do
 					table.insert(nt, arg[j])
 				end
-				onswitch[longopt](table.unpack(nt))
+				print('onsw')
 			elseif nargs == 1 then
 				onswitch[longopt](arg[i+1])
+			else
+				onswitch[longopt]()
 			end
 			i = i + nargs
 		end
 		if v == '--' then
 			keepParsing = false
@@ -175,11 +181,11 @@
 				if keepParsing and v:sub(1,1) == '-' then
 					for c,p in ss.str.enc.utf8.each(v:sub(2)) do
 						if optmap[c] then
 							execLongOpt(optmap[c])
 						else
-							ct.exns.cli('switch -%i unrecognized', c):throw()
+							ct.exns.cli('switch -%s unrecognized', c):throw()
 						end
 					end
 				else
 					table.insert(args, v)
 				end

Index: cortav.lua
==================================================================
--- cortav.lua
+++ cortav.lua
@@ -10,10 +10,68 @@
 local dump = ss.dump
 local declare = ss.declare
 
 -- make this module available to require() when linked into a lua bytecode program with luac
 local ct = ss.namespace 'cortav'
+ct.info = {
+	version = ss.version {0,1; 'devel'};
+	package_name = 'cortav';
+	contributors = {
+		{ name = 'lexi hale', handle = 'velartrill';
+		  mail = 'lexi@hale.su', homepage = 'https://hale.su' };
+	};
+	ident_string = function(i)
+		return string.format('%s %s', i.package_name, i.version)
+	end;
+	credits = function(i)
+		local all = ss.copy(i.contributors)
+		for i,who in pairs(all) do
+			who.role = who.role or 'core functionality'
+		end
+		for name,ext in pairs(ct.ext.loaded) do
+			if ext.contributors then
+				for _,c in pairs(ext.contributors) do
+					local ofs, ref = ss.find(all, function(a)
+						return a.handle == c.handle
+					end)
+					if ofs then
+						ref.role = string.format('%s; %s extension', ref.role, name)
+					else
+						local c = ss.clone(ext.author)
+						c.role = name .. ' extension'
+					end
+				end
+			end
+		end
+		return all
+	end;
+	credits_ascii = function(contributors)
+		local body = ''
+		for _, c in pairs(contributors) do
+			local str
+			if c.handle then
+				str = string.format('%s “%s” <%s>', c.name, c.handle, c.mail)
+			else
+				str = string.format('%s <%s>', c.name, c.mail)
+			end
+			if c.homepage then
+				str = string.format('%s (%s)', str, c.homepage)
+			end
+			if c.role then
+				str = string.format('%s: %s', str, c.role)
+			end
+			body = body .. string.format(' ~ %s\n', str)
+		end
+		return body
+	end;
+	about = function(i)
+		return i:ident_string() .. '\n' ..
+		       i.credits_ascii(i:credits())
+	end;
+}
+
+
 ct.render = {}
 
 ct.exns = {
 	tx = ss.exnkind('translation error', function(msg,...)
 		return string.format("(%s:%u) "..msg, ...)

Index: ext/toc.lua
==================================================================
--- ext/toc.lua
+++ ext/toc.lua
@@ -2,9 +2,11 @@
 local ss = require 'sirsem'
 
 ct.ext.install {
 	id = 'toc';
 	desc = 'provides a table of contents for HTML renderer plus generic fallback';
+	version = ss.version {0,1; 'devel'};
+	contributors = {{name='lexi hale', handle='velartrill', mail='lexi@hale.su', homepage='https://hale.su'}};
 	directive = function(words)
 
 	end;
 }

Index: sirsem.lua
==================================================================
--- sirsem.lua
+++ sirsem.lua
@@ -37,10 +37,67 @@
 	for i, v in ipairs(list) do
 		if fn(v,i) then table.insert(new, v) end
 	end
 	return new
 end
+function ss.kmap(fn, list)
+	local new = {}
+	for k, v in pairs(list) do
+		local nk,nv = fn(k,v)
+		new[nk or k] = nv or v
+	end
+	return new
+end
+
+function ss.kfilter(list, fn)
+	local new = {}
+	for k, v in pairs(list) do
+		if fn(k,v) then new[k] = v end
+	end
+	return new
+end
+
+function ss.find(tbl, pred, ...)
+	pred = pred or function(a,b)
+		return a == b
+	end
+	for k,v in pairs(tbl) do
+		if pred(v,k,...) then return k,v end
+	end
+	return nil
+end
+
+function ss.clone(tbl) -- performs a shallow copy
+	if tbl.clone then return tbl:clone() end
+	local new = {}
+	for k,v in pairs(tbl) do
+		new[k] = v
+	end
+	return new
+end
+
+function ss.copy(tbl) -- performs a deep copy
+	local new = {}
+	for k,v in pairs(tbl) do
+		if type(v) == 'table' then
+			if v.clone then
+				new[k] = v:clone() -- this may or may not do a deep copy!
+			else
+				new[k] = ss.copy(v)
+			end
+		else
+			new[k] = v
+		end
+	end
+	return new
+end
+
+function ss.delegate(tbl,tpl) -- returns a table that looks up keys it lacks from
+                              -- tbl (lightweight alternative to shallow copies)
+	tpl = tpl or {}
+	return setmetatable({}, {__index=tbl})
+end
 
 ss.str = {}
 
 function ss.str.begins(str, pfx)
 	return string.sub(str, 1, #pfx) == pfx
@@ -270,5 +327,44 @@
 		end
 	end
 
 	ss.str.exn('token “%s” expected before end of line', stop):throw()
 end
+
+ss.version = ss.declare {
+	name = 'version';
+	mk = function(tbl) return tbl end;
+	fns = {
+		pre = function(self,other) end;
+		post = function(self,other) end;
+		string = function(self) return tostring(self) end;		
+	};
+	cast = {
+		string = function(vers)
+			if not(next(vers)) then return '0.0' end
+			local str = ''
+			for _,v in pairs(vers) do
+				if type(v) == 'string' then
+					if str ~= '' then str = str .. '-' end
+					str = str .. v
+				else
+					if str ~= '' then str = str .. '.' end
+					str = str .. tostring(v)
+				end
+			end
+			return str
+		end
+	};
+}
+
+function ss.classinstance(o)
+	local g = getmetatable(o)
+	if not o then return nil end
+	local mm = getmetatable(g)
+	if not o then return nil end
+	if mm.__name == 'class' then
+		return g
+	else
+		return nil
+	end
+end
+