Move anselme code into its own directory

anselme/stdlib/closure.lua

@@ -0,0 +1,38 @@
+local ast = require("anselme.ast")
+local Nil, Boolean, Definition = ast.Nil, ast.Boolean, ast.Definition
+
+return {
+	{
+		"defined", "(c::closure, s::string)",
+		function(state, c, s)
+			return Boolean:new(c.exported_scope:defined_in_current_strict(state, s:to_identifier()))
+		end
+	},
+	{
+		"_._", "(c::closure, s::string)",
+		function(state, c, s)
+			local identifier = s:to_identifier()
+			assert(c.exported_scope:defined_in_current_strict(state, identifier), ("no exported variable %q defined in closure"):format(s.string))
+			return c.exported_scope:get(state, identifier)
+		end
+	},
+	{
+		"_._", "(c::closure, s::string) = v",
+		function(state, c, s, v)
+			local identifier = s:to_identifier()
+			assert(c.exported_scope:defined_in_current_strict(state, identifier), ("no exported variable %q defined in closure"):format(s.string))
+			c.exported_scope:set(state, identifier, v)
+			return Nil:new()
+		end
+	},
+	{
+		"_._", "(c::closure, s::symbol) = v",
+		function(state, c, s, v)
+			assert(s.exported, "can't define a non-exported variable from the outside of the closure")
+			state.scope:push(c.exported_scope)
+			local r = Definition:new(s, v):eval(state)
+			state.scope:pop()
+			return r
+		end
+	}
+}