Hyskell

This brings two functional-ish things to Hy: accumulating for loops and unions/pattern matching. Just prefix your files with this:

(require hyskell)

accfor

accfor is a for loop that is actually an iterator. It's basically genexpr with a nicer syntax that can take anything; not just a single expression.

(print (list (accfor [x [1 2 3]] x))) ; prints [1 2 3]

defunion

Defines a union type:

(defunion Node
  (Nint val)
  (Nstr val))

This example defines three types: Node (a base class), Nint (a class with one attribute: val), and Nstr (same as Nint).

You can use the types like any other type:

(setv i (Nint 7))
(setv s (Nstr "abc"))

match

True ML-style pattern matching:

(match value
  [[1 2 3] (print "Got list [1 2 3]")] ; against a list
  [[:a 2 3] (print "Got list with a =" a)] ; grab values with :
  [(, 1 2) (print "Got tuple (1, 2)")] ; against a tuple
  [1 (print "Got 1")] ; against an int or string
  [(Nint :v) (print "Got Nint with v =" v)] ; against a union branch
  [(Nstr (:val "abc")) (print "Got Nstr with val of abc")] ; use : at the beginning of an expression to test attributes
  [(Nstr _) (print "Got Nstr")] ; use _ to ignore values
  [[1 2 ...] (print "Got list that starts with 1 and 2")] ; use ... to allow extra items at the end
  [[_ _ ...] (print "Got list with >= 2 elements")] ; use ... with _ to do cool stuff
  [_ (print "Got something weird!")]) ; you can also use _ for a fallthrough statement

If none of the branches match, a hyskell.MatchFailure exception is thrown.

Examples

See test_hyskell.hy for the unit tests, written using HyTest.