anchor.diff:    */
     flip = f: a: b: f b a;
   
  -  /* Apply function if argument is non-null.
  +  /* Apply function if the supplied argument is non-null.
   
        Example:
          mapNullable (x: x+1) null
  
positive.code:      second subtype, compare elements of a single subtype with `yes`
       and `no` respectively.
  
       Example:
  
         let cmp = splitByAndCompare (hasPrefix "foo") compare compare; in
  
         cmp "a" "z" => -1
  
negative.code: 
       Type: id :: a -> a
    */
    id =
      # The value to return
      x: x;
  
    /* The constant function
  
       Ignores the second argument. If called with only one argument,
       constructs a function that always returns a static value.
  
       Type: const :: a -> b -> a
       Example:
         let f = const 5; in f 10
         => 5
    */
    const =
      # Value to return
      x:
      # Value to ignore
      y: x;
  
  
    ## Named versions corresponding to some builtin operators.
  
    /* Concatenate two lists
  
       Type: concat :: [a] -> [a] -> [a]
  
       Example:
         concat [ 1 2 ] [ 3 4 ]
         => [ 1 2 3 4 ]
    */
    concat = x: y: x ++ y;
  
    /* boolean “or” */
  