diff --git a/gitlab-pages/docs/language-basics/maps-records.md b/gitlab-pages/docs/language-basics/maps-records.md index 1f49d318c..4139db6e9 100644 --- a/gitlab-pages/docs/language-basics/maps-records.md +++ b/gitlab-pages/docs/language-basics/maps-records.md @@ -230,6 +230,106 @@ xy_translate "({x:2,y:3,z:1}, {dx:3,dy:4})" You have to understand that `p` has not been changed by the functional update: a nameless new version of it has been created and returned. +#### Nested updates + +A unique feature of LIGO is the ability to perform nested updates on records. + +For example if you have the following record structure: + + + +```pascaligo +type color is +| Blue +| Green + +type preferences is record [ + color : color; + other : int; +] + +type account is record [ + id : int; + preferences : preferences; +] +``` + + + + +```cameligo +type color = + Blue +| Green + +type preferences = { + color : color; + other : int; +} + +type account = { + id: int; + preferences: preferences; +} +``` + + + + +```reasonligo +type color = + Blue +| Green; + +type preferences = { + color : color, + other : int +} + +type account = { + id : int, + preferences : preferences +} +``` + + + +You can update the nested record with the following code: + + + +```pascaligo + +function change_color_preference (const account : account; const color : color ) : account is + block { + account := account with record [preferences.color = color] + } with account + +``` + + + + +```cameligo +let change_color_preference (account : account) (color : color) : account = + { account with preferences.color = color } +``` + + + + +```reasonligo +let change_color_preference = (account : account, color : color): account => + { ...account, preferences.color: color }; +``` + + + +Note that all the records in the path will get updated. In this example that's +`account` and `preferences`. + + + ### Record Patches Another way to understand what it means to update a record value is to @@ -318,6 +418,8 @@ xy_translate "(record [x=2;y=3;z=1], record [dx=3;dy=4])" The hiding of a variable by another (here `p`) is called `shadowing`. + + ## Maps *Maps* are a data structure which associate values of the same type to