struct EvalResult
car(void *param, Gc *gc, struct Scope *scope, struct Expr args);
struct EvalResult eval(Gc *gc, struct Scope *scope, struct Expr expr);
struct EvalResult
car(void *param, Gc *gc, struct Scope *scope, struct Expr args);
struct EvalResult eval(Gc *gc, struct Scope *scope, struct Expr expr);