%whites =/([ \t]*(?:#.*)?)/ 
%token VAR =/([A-Za-z][A-Za-z0-9_]*)/ 

%%

def:
      param_spec return_spec ',' 
;
param_spec:
      type
    | name_list ':' type 
;
return_spec:
      type
    | name ':' type 
;
type:
      VAR 
;
name:
      VAR 
;
name_list:
      name
    | name ',' name_list 
;

%%