commit 0feea2dbd2eb76ffa1ba1db7d291bcb1a274d529 · pyrox.dev/nixpkgs

+21
nixos/doc/manual/development/option-types.section.md
···

       42
       42
        
       :   One element of the list *`l`*, e.g. `types.enum [ "left" "right" ]`.

     

       43
       43
        
           Multiple definitions cannot be merged.

     

       44
       44
        
       

     

       45
       45
       +
           If you want to pair these values with more information, possibly of

     

       46
       46
       +
           distinct types, consider using a [sum type](#sec-option-types-sums).

     

       47
       47
       +
       

     

       45
       48
        
       `types.anything`

     

       46
       49
        
       

     

       47
       50
        
       :   A type that accepts any value and recursively merges attribute sets

     
···

       278
       281
        
           user to affect all submodules in an `attrsOf submodule` at once. This is

     

       279
       282
        
           more convenient and discoverable than expecting the module user to

     

       280
       283
        
           type-merge with the `attrsOf submodule` option.

     

       284
       284
       +
       

     

       285
       285
       +
       ## Union types {#sec-option-types-unions}

     

       286
       286
       +
       

     

       287
       287
       +
       A union of types is a type such that a value is valid when it is valid for at least one of those types.

     

       288
       288
       +
       

     

       289
       289
       +
       If some values are instances of more than one of the types, it is not possible to distinguish which type they are meant to be instances of. If that's needed, consider using a [sum type](#sec-option-types-sums).

     

       290
       290
       +
       

     

       291
       291
       +
       

     

       292
       292
       +
       

     

       293
       293
       +
       ## Sum types {#sec-option-types-sums}

     

       294
       294
       +
       

     

       295
       295
       +
       A sum type can be thought of, conceptually, as a *`types.enum`* where each valid item is paired with a type, through some value syntax.

     

       296
       296
       +
       Nix does not have a built-in syntax for this pairing of a label and a type or value, so sum types may be represented in multiple ways.

     

       297
       297
       +
       

     

       298
       298
       +
       If the built-in Nix value types provide enough distinction, you simplify your syntax with a [union type](#sec-option-types-unions) instead.

     

       299
       299
       +
       

     

       300
       300
       +
       

     

       301
       301
       +
       

     

       281
       302
        
       

     

       282
       303
        
       ## Composed types {#sec-option-types-composed}

     

       283
       304