Pattern matching

[macobo]

Pattern matching seems to be broken since 774461c, where also most of the tests got removed.

For example, the following code prints None on current revision (from readme):

from macropy.macros.pattern import macros, patterns
from macropy.macros.adt import macros, case

@case
class Rect(p1, p2): pass

@case
class Line(p1, p2): pass

@case
class Point(x, y): pass

def area(rect):
    with patterns:
        Rect(Point(x1, y1), Point(x2, y2)) << rect
        return (x2 - x1) * (y2 - y1)

print area(Rect(Point(1, 1), Point(3, 3))) # 4

The python code created (by unparse_ast) is following. Note the area function.

import inspect
from ast import *
from macropy.core import util
from macropy.core.macros import *
from macropy.core.lift import *
from macropy.core.lift import *
macros = Macros()

class PatternMatchException(Exception):
    '\n    Thrown when a nonrefutable pattern match fails\n    '
    pass

# snip, edited for brevity

@link_children
class Point(CaseClass):

    def __init__(self, *args, **kwargs):
        CaseClass.__init__(self, *args, **kwargs)
        pass
    _children = []
    _fields = ['x', 'y']

def area(rect):
    None
print area(Rect(Point(1, 1), Point(3, 3)))

[lihaoyi]

Ack, it looks like I screwed up a merge somewhere. Give me some time and I'll try to dig up the working version from the git history.

[lihaoyi]

Fixed it, I think 316b4ac

[macobo]

Nope, sorry, this still doesn't work. Two new testcases for pattern_test.py that fail:

    def test_block_entered(self):
        " See https://github.com/lihaoyi/macropy/issues/40 "
        with patterns:
            return
        raise Exception("with block not entered")

    def test_pattern_function(self):
        def sum(foo):
            with patterns:
                Foo(x, y) << foo
                return x + y
        self.assertEquals(sum(Foo(1, 2)), 3)

[lihaoyi]

Hmmm lemme take another look

[macobo]

No hurry, I'll be busy with other things for a few days.

[lihaoyi]

@jnhnum1 could you take a look at this?

[jnhnum1]

yeah, I'm at work now but I'll take a look at it later tonight.

[lihaoyi]

I'm guessing we'll need to do this (#15) before we can be really confident of pattern matching working in the general case.

[lihaoyi]

I moved pattern matching (together with TCO) into /macropy/experimental/ in the last reshuffling, since it doesn't seem very stable or reliable at this point. We'll put it back into /macropy/ after we close this and #15.

[lihaoyi]

Sorry, I probably screwed up more than one thing while doing the big refactorings (e.g. converting how block macros work)