···

       
241
       
 
       


     

       
242
       
 
       
  /* Return a singleton list or an empty list, depending on a boolean

     

       
243
       
 
       
     value.  Useful when building lists with optional elements

     

       
244
       
-
       
     (e.g. `++ optional (system == "i686-linux") flashplayer').

     

       
245
       
 
       


     

       
246
       
 
       
     Type: optional :: bool -> a -> [a]

     

       
247
       
 
       


     

···

       
241
       
 
       


     

       
242
       
 
       
  /* Return a singleton list or an empty list, depending on a boolean

     

       
243
       
 
       
     value.  Useful when building lists with optional elements

     

       
244
       
+
       
     (e.g. `++ optional (system == "i686-linux") firefox').

     

       
245
       
 
       


     

       
246
       
 
       
     Type: optional :: bool -> a -> [a]

     

       
247