package main import ( "fmt" "reflect" ) type special func(*environment, ...interface{}) (interface{}, error) func define(env *environment, args ...interface{}) (interface{}, error) { if len(args) != 2 { return nil, fmt.Errorf(`received %d arguments in *define*, expected exactly 2`, len(args)) } s, ok := args[0].(symbol) if !ok { return nil, fmt.Errorf(`first argument to *define* must be symbol, received %v`, reflect.TypeOf(args[0])) } env.set(s, args[1]) return nil, nil } func quote(_ *environment, args ...interface{}) (interface{}, error) { return sexp(args), nil }