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https://github.com/refi64/hyskell

Union types and some other functional-y stuff for Hy
https://github.com/refi64/hyskell

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Union types and some other functional-y stuff for Hy

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Hyskell
=======

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

.. code-block:: hy

(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.

.. code-block:: hy

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

defunion
********

Defines a union type:

.. code-block:: hy

(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:

.. code-block:: hy

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

match
*****

True ML-style pattern matching:

.. code-block:: hy

(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 `_.