#!/usr/bin/env python
# -*- coding: utf-8 -*-
from tree import Tree
import itertools
"""
Types: Constants defined for each type:
S-expression
├── list -------------> quote ()
└── number -----------> 0
"""
type_tree = Tree.from_tuple(('S-expression',
('list',),
('number',)))
def descendant_combinations(types):
return itertools.product(*[type_tree.find(e).descendants() for e in types])
# List of primitive functions along with their type contract
primitives = {
#name : ((input_types,), output_type)
'list?' : (('S-expression',), 'number'),
'if' : (('S-expression', 'S-expression',
'S-expression'), 'S-expression'),
'car' : (('list',), 'S-expression'),
'cdr' : (('list',), 'list'),
'cons' : (('S-expression', 'list'), 'list'),
'succ' : (('number',), 'number'),
'pred' : (('number',), 'number'),
# Literals
