···

       
299
       
299
       
 
       
    `with types; oneOf [ int str bool ]`. Multiple definitions cannot be

     

       
300
       
300
       
 
       
    merged.

     

       
301
       
301
       
 
       


     

       
302
       
302
       
+
       
`types.nullOr` *`t`*

     

       
303
       
303
       
+
       


     

       
304
       
304
       
+
       
:   `null` or type *`t`*. Multiple definitions are merged according to

     

       
305
       
305
       
+
       
    type *`t`*.

     

       
306
       
306
       
+
       


     

       
302
       
307
       
 
       


     

       
303
       
308
       
 
       
## Sum types {#sec-option-types-sums}

     

       
304
       
309
       
 
       


     
···

       
352
       
357
       
 
       
    type of `foo.attr` was `lazyAttrsOf (nullOr int)`, `null` would be

     

       
353
       
358
       
 
       
    returned instead for the same `mkIf false` definition.

     

       
354
       
359
       
 
       
    :::

     

       
355
       
355
       
-
       


     

       
356
       
356
       
-
       
`types.nullOr` *`t`*

     

       
357
       
357
       
-
       


     

       
358
       
358
       
-
       
:   `null` or type *`t`*. Multiple definitions are merged according to

     

       
359
       
359
       
-
       
    type *`t`*.

     

       
360
       
360
       
 
       


     

       
361
       
361
       
 
       
`types.uniq` *`t`*

     

       
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362