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empty?

empty? returns true if the given value is "empty-ish". The following values are considered "empty-ish":

  • null
  • bool: false
  • number: 0 (integer) and 0.0 (float)
  • string: "" (string of zero length)
  • vector: [] (vector with 0 elements)
  • object: {} (object with 0 elements)

empty? is primarily intended to deal with malformed/maltyped JSON data.

Examples

  • (empty? "") ➜ true
  • (empty? 42) ➜ false

Forms

(empty? value:any) ➜ bool

  • value is exactly 1 expression.

The expression is evaluated and if it's empty-ish according to the list above, true is returned, else false. The expression must be evaluatable, so identifiers cannot be used ((empty? to-upper) is invalid).

If the expression errors out, empty? also returns an error.

Context

empty? evaluates the expression in its own scope, so variables defined in it do not leak.