delete.md

delete

delete removes a key from an object or an item from a vector (shrinking that vector by 1 element). It must be used on any expression that has a path expression attached (e.g. (delete (do-something).gone)).

Note that delete is, like all functions in Rudi, stateless and so does not modify the given argument directly. That is why delete can be used on non-variables/documents, like in (delete (read-config).password) to get rid of individual keys from a larger data structure. To enable this, delete always returns the remaining datastructure, not the value that was removed.

To make your changes "stick", use the bang modifier: (delete! $var.foo) – this only makes sense for symbols (i.e. variables and the global document), since there is no "source" to be updated for e.g. literals (hence (delete! [1 2 3][1]) is invalid).

set is another function that is most often used with the bang modifier and also returns the entire datastructure, not just the newly inserted value.

Examples

• (delete! $var.key)
• (delete! .[1])

This function is mostly used with the bang modifier, but can sometimes also be useful without if you only want to modify an object/vector "in transit":

• (connect (delete (read-config).isAdmin)) to give connect a config object object without the isAdmin flag.

Forms

(delete target:pathed) ➜ any

• target is a any expression with a path expression.

delete evaluates the target expression and then removes whatever the path expression is pointing to. The return value is the remaining data (i.e. not the removed value).

When used with the bang modifier, target must be a symbol with a path expression.