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doc/option-types: Move attrTag to Sum types, remove redundant paragraph

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Robert Hensing 2024-01-28 16:24:59 +01:00
parent 2ceb5558f9
commit 1ad30772ea
1 changed files with 4 additions and 10 deletions
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14
nixos/doc/manual/development/option-types.section.md
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@ -307,7 +307,11 @@ Nix does not have a built-in syntax for this pairing of a label and a type or va
If the built-in Nix value types provide enough distinction, you simplify your syntax with a [union type](#sec-option-types-unions) instead.
`types.attrTag` *`{ attr1 = t1; attr2 = t2; ... }`*
: An attribute set containing one attribute, whose name must be picked from
the attribute set (`attr1`, etc) and whose value must be of the accompanying
type.
## Composed types {#sec-option-types-composed}
@ -365,16 +369,6 @@ Composed types are types that take a type as parameter. `listOf
the line `The option <option path> is defined multiple times.` and before
a list of definition locations.
`types.attrTag` *`{ attr1 = t1; attr2 = t2; ... }`*
: An attribute set containing one attribute, whose name must be picked from
the attribute set (`attr1`, etc) and whose value must be of the accompanying
type.
This is one possible representation of what may be called a _tagged union_ or _sum type_.
`attrTag` can be thought of as an extension of *`enum`* where the permissible items
are attribute names, and each item is paired with a value of a specific type.
`types.coercedTo` *`from f to`*
: Type *`to`* or type *`from`* which will be coerced to type *`to`* using