match

    macro
    boot.janet on line 1613, column 1

    (match x & cases)

    Pattern matching. Match an expression `x` against any number of 
    cases. Each case is a pattern to match against, followed by an 
    expression to evaluate to if that case is matched. Legal patterns 
    are:

    * symbol -- a pattern that is a symbol will match anything, binding 
      `x`'s value to that symbol.

    * array -- an array will match only if all of its elements match 
      the corresponding elements in `x`.

    * table or struct -- a table or struct will match if all values 
      match with the corresponding values in `x`.

    * tuple -- a tuple pattern will match if its first element matches, 
      and the following elements are treated as predicates and are 
      true.

    * `_` symbol -- the last special case is the `_` symbol, which is a 
      wildcard that will match any value without creating a binding.

    Any other value pattern will only match if it is equal to `x`.