Mutable variables in FQL

[ptpaterson]

You can… if you really want to… provide the same variable multiple times to a Let.

Is there anyway to write a switch statement in FQL for UDF?

You might still want to put guards around each case, want to avoid query failure for bad data, or otherwise do not want to run every case. Let can accept an array of bindings, a useful trick to reuse variables in subsequent expressions. Here is a switch, put together with some helper methods. const matchCase = (testValue, expr) => q.If( q.IsNull(q.Var('_case')), q.If(q.Equals(testValue, q.Var('_switch')), expr, null), q.Var('_case') ); const defaultCase = (expr) => q.If(q.I…

And shadowing/scoping is indeed SUPER useful in building deep hierarchical queries. This is just using the same variable in a Let inside the previous Let.