How to use [switch]

The reference page of switch has its arguments, constraints and declaration.

[switch] works similarly to a switch/case block in a traditional programming language, and will find the first [case] node with a value matching the evaluated value of the [switch] node, and execute that [case] node as a lambda object.

.val:foo
.result
switch:x:@.val

   case:bar
      set-value:x:@.result
         .:Oops

   case:foo
      set-value:x:@.result
         .:Success!

[switch] can only contain two types of children nodes; [case] and [default]. The [default] node will be evaluated if none of the [case] node’s values are matching the evaluated value of your [switch]. Try evaluating the following in your “Eval” component to understand this.

.val:fooXX
.result
switch:x:@.val

   case:bar
      set-value:x:@.result
         .:Oops

   case:foo
      set-value:x:@.result
         .:Oops2.0

   default
      set-value:x:@.result
         .:Success!

In the above, the expression evaluated in the switch, which is @.val will become “fooXX” after evaluating it. None of its children [case] nodes contains this as an option, hence the [default] node will be evaluated, and this results in setting the [.result] node’s value to “Success!”.

[default] cannot have a value, and all your [case] nodes must have a value, either a constant or an expression. However, any types can be used as values for your [case] nodes. And your [switch] node must at the very least have minimum one [case] node. The [default] node is optional though. You can mix and match different types as you see fit in your [case] nodes.