miniadt

how to use

## create Type

>>> from miniadt import ADTTypeProvider
>>> TreeType = ADTTypeProvider("Tree")

>>> Node = TreeType("Node", "e children")
>>> Leaf = TreeType("Leaf", "e")


## printing value

>>> Leaf(e=10)
Leaf(e=10)
>>> Node(e=10, children=[Leaf(e=20)])
Node(e=10, children=[Leaf(e=20)])


## use pattern match

>>> @TreeType.match
... class depth(object):
...     def Node(e, children):
...         return max(depth(e)for e in children) + 1
...
...     def Leaf(e):
...         return 1

>>> depth(Leaf(e=10))
1

>>> depth(Node(e=10, children=[Leaf(e=20), Node(e=30, children=[Leaf(e=40)])]))
3

miniadt has comprehensive check function.

## not comprehensive definition on pattern matching function error is occur

### 1. lack of dispatch andidates
>>> class invalid_dispatch(object):
...     def Node(e, children):
...         return "foo"

>>> TreeType.match(invalid_dispatch)
Traceback (most recent call last):
 ...
miniadt.NotComprehensive: Leaf is not found. expected=['Node', 'Leaf']


### 2. dispatch function's arguments are invalid.
>>> class invalid_dispatch2(object):
...     def Node(e):  ## correct argsspec is "e, children"
...         return "foo"
...     def Leaf(e):
...         return "foo"

>>> TreeType.match(invalid_dispatch2)
Traceback (most recent call last):
 ...
miniadt.NotComprehensive: on Tree.Node:  expected=['e', 'children'] != actual=['e']

from miniadt import ADTTypeProvider
Tree = ADTTypeProvider("Tree")
Node = Tree("Node", "e children")
Leaf = Tree("Leaf", "e")

print(Leaf(e=10))  # => Leaf(e=10)
print(Node(e=10, children=[Leaf(e=20)]))  # => Node(e=10, children=[Leaf(e=20)])


@Tree.match
class depth(object):
    def Leaf(e):
        return 1

    def Node(e, children):
        return max(depth(e) for e in children) + 1


print(depth(Leaf(e=10)))  # => 10
print(depth(Node(e=10, children=[Leaf(e=20)])))  # 2


@Tree.match_instance
class Applicator(object):
    def __init__(self, name):
        self.name = name

    def Leaf(self, e):
        return self.name

    def Node(self, e, children):
        return [self.name, [self(x) for x in children]]

print(Applicator("foo")(Leaf(e=10)))  # => foo
print(Applicator("foo")(Node(e=10, children=[Leaf(e=20)])))  # => ['foo', ['foo']]


@Tree.classify
class ToDict(object):
    def Leaf(self, leaf):
        return leaf.e

    def Node(self, node):
        return {"e": node.e, "children": [self(e) for e in node.children]}

todict = ToDict()
print(todict(Leaf(e=10)))  # => 10
print(todict(Node(e=10, children=[Leaf(e=20)])))  # => {'e': 10, 'children': [20]}