move stack code up under interp & minor edits
This commit is contained in:
Simon Forman
parent
20c4b90298
commit
d7f047cee6
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@ -75,6 +75,141 @@ def joy(stack, expr, dictionary):
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return stack, expr, dictionary
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'''
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███████╗████████╗ █████╗ ██████╗██╗ ██╗
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██╔════╝╚══██╔══╝██╔══██╗██╔════╝██║ ██╔╝
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███████╗ ██║ ███████║██║ █████╔╝
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╚════██║ ██║ ██╔══██║██║ ██╔═██╗
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███████║ ██║ ██║ ██║╚██████╗██║ ██╗
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╚══════╝ ╚═╝ ╚═╝ ╚═╝ ╚═════╝╚═╝ ╚═╝
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When talking about Joy we use the terms "stack", "quote", "sequence",
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"list", and others to mean the same thing: a simple linear datatype that
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permits certain operations such as iterating and pushing and popping
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values from (at least) one end.
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In describing Joy I have used the term quotation to describe all of the
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above, because I needed a word to describe the arguments to combinators
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which fulfill the same role in Joy as lambda abstractions (with
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variables) fulfill in the more familiar functional languages. I use the
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term list for those quotations whose members are what I call literals:
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numbers, characters, truth values, sets, strings and other quotations.
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All these I call literals because their occurrence in code results in
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them being pushed onto the stack. But I also call [London Paris] a list.
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So, [dup *] is a quotation but not a list.
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`"A Conversation with Manfred von Thun" w/ Stevan Apter <http://archive.vector.org.uk/art10000350>`_
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There is no "Stack" Python class, instead we use the `cons list`_, a
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venerable two-tuple recursive sequence datastructure, where the empty
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tuple ``()`` is the empty stack and ``(head, rest)`` gives the recursive
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form of a stack with one or more items on it::
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stack := () | (item, stack)
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Putting some numbers onto a stack::
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Joy Python
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[] ()
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[1] (1, ())
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[2 1] (2, (1, ()))
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[3 2 1] (3, (2, (1, ())))
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...
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Python has very nice "tuple packing and unpacking" in its syntax which
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means we can directly "unpack" the expected arguments to a Joy function.
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We assign the argument stack to the expected structure of the stack and
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Python takes care of unpacking the incoming tuple and assigning values to
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the names. (Note that Python syntax doesn't require parentheses around
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tuples used in expressions where they would be redundant.)
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def dup(stack):
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head, tail = stack
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return head, (head, tail)
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.. _cons list: https://en.wikipedia.org/wiki/Cons#Lists
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'''
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def list_to_stack(el, stack=()):
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'''
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Convert a Python list (or other sequence) to a Joy stack::
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[1, 2, 3] -> (1, (2, (3, ())))
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:param list el: A Python list or other sequence (iterators and generators
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won't work because ``reversed()`` is called on ``el``.)
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:param stack stack: A stack, optional, defaults to the empty stack. This
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allows for concatinating Python lists (or other sequence objects)
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onto an existing Joy stack.
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:rtype: stack
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'''
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for item in reversed(el):
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stack = item, stack
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return stack
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def iter_stack(stack):
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'''
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Iterate through the items on the stack.
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:param stack stack: A stack.
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:rtype: iterator
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'''
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while stack:
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item, stack = stack
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yield item
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def concat(quote, expression):
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'''
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Concatinate quote onto expression.
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In joy [1 2] [3 4] would become [1 2 3 4].
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:param stack quote: A stack.
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:param stack expression: A stack.
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:rtype: stack
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'''
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isnt_stack(quote)
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isnt_stack(expression)
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return list_to_stack(list(iter_stack(quote)), expression)
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## return (quote[0], concat(quote[1], expression)) if quote else expression
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# :raises RuntimeError: if quote is larger than sys.getrecursionlimit().
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# This is the fastest implementation but it would trigger
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# RuntimeError: maximum recursion depth exceeded
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# on quotes longer than sys.getrecursionlimit().
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def get_n_items(n, stack):
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'''
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Return items and remainder of stack.
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Raise StackUnderflowError if there are fewer than n items on the stack.
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'''
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assert n > 0, repr(n)
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temp = []
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while n > 0:
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n -= 1
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try:
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item, stack = stack
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except ValueError:
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raise StackUnderflowError('Not enough values on stack.') from None
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temp.append(item)
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temp.append(stack)
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return tuple(temp)
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def reversed_stack(stack):
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'''
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Return list_reverseiterator object for a stack.
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'''
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return reversed(list(iter_stack(stack)))
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'''
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██████╗ █████╗ ██████╗ ███████╗███████╗██████╗
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██╔══██╗██╔══██╗██╔══██╗██╔════╝██╔════╝██╔══██╗
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@ -196,160 +331,6 @@ def _parse(tokens):
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return list_to_stack(frame)
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r'''
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███████╗████████╗ █████╗ ██████╗██╗ ██╗
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██╔════╝╚══██╔══╝██╔══██╗██╔════╝██║ ██╔╝
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███████╗ ██║ ███████║██║ █████╔╝
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╚════██║ ██║ ██╔══██║██║ ██╔═██╗
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███████║ ██║ ██║ ██║╚██████╗██║ ██╗
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╚══════╝ ╚═╝ ╚═╝ ╚═╝ ╚═════╝╚═╝ ╚═╝
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When talking about Joy we use the terms "stack", "quote", "sequence",
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"list", and others to mean the same thing: a simple linear datatype that
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permits certain operations such as iterating and pushing and popping
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values from (at least) one end.
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In describing Joy I have used the term quotation to describe all of the
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above, because I needed a word to describe the arguments to combinators
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which fulfill the same role in Joy as lambda abstractions (with
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variables) fulfill in the more familiar functional languages. I use the
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term list for those quotations whose members are what I call literals:
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numbers, characters, truth values, sets, strings and other quotations.
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All these I call literals because their occurrence in code results in
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them being pushed onto the stack. But I also call [London Paris] a list.
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So, [dup \*] is a quotation but not a list.
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`"A Conversation with Manfred von Thun" w/ Stevan Apter <http://archive.vector.org.uk/art10000350>`_
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There is no "Stack" Python class, instead we use the `cons list`_, a
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venerable two-tuple recursive sequence datastructure, where the
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empty tuple ``()`` is the empty stack and ``(head, rest)`` gives the
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recursive form of a stack with one or more items on it::
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stack := () | (item, stack)
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Putting some numbers onto a stack::
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()
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(1, ())
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(2, (1, ()))
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(3, (2, (1, ())))
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...
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Python has very nice "tuple packing and unpacking" in its syntax which
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means we can directly "unpack" the expected arguments to a Joy function.
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We assign the argument stack to the expected structure of the stack and
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Python takes care of unpacking the
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incoming tuple and assigning values to the names. (Note that Python
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syntax doesn't require parentheses around tuples used in expressions
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where they would be redundant.)
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def dup(stack):
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head, tail = stack
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return head, (head, tail)
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We have two very simple functions, one to build up a stack from a Python
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list and another to iterate through a stack and yield its items
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one-by-one in order. There are also two functions to generate string representations
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of stacks. They only differ in that one prints the terms in stack from left-to-right while the other prints from right-to-left. In both functions *internal stacks* are
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printed left-to-right. These functions are written to support :doc:`../pretty`.
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.. _cons list: https://en.wikipedia.org/wiki/Cons#Lists
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'''
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def list_to_stack(el, stack=()):
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'''
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Convert a Python list (or other sequence) to a Joy stack::
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[1, 2, 3] -> (1, (2, (3, ())))
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:param list el: A Python list or other sequence (iterators and generators
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won't work because ``reverse()`` is called on ``el``.)
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:param stack stack: A stack, optional, defaults to the empty stack. This
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allows for concatinating Python lists (or other sequence objects)
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onto an existing Joy stack.
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:rtype: stack
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'''
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for item in reversed(el):
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stack = item, stack
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return stack
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def iter_stack(stack):
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'''
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Iterate through the items on the stack.
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:param stack stack: A stack.
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:rtype: iterator
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'''
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while stack:
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item, stack = stack
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yield item
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def concat(quote, expression):
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'''
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Concatinate quote onto expression.
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In joy [1 2] [3 4] would become [1 2 3 4].
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:param stack quote: A stack.
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:param stack expression: A stack.
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:rtype: stack
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'''
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# This (below) is the fastest implementation, but will trigger
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# RuntimeError: maximum recursion depth exceeded
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# on quotes longer than sys.getrecursionlimit().
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# :raises RuntimeError: if quote is larger than sys.getrecursionlimit().
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## return (quote[0], concat(quote[1], expression)) if quote else expression
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# Original implementation.
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## return list_to_stack(list(iter_stack(quote)), expression)
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# In-lining is slightly faster (and won't break the
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# recursion limit on long quotes.)
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isnt_stack(quote)
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isnt_stack(expression)
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temp = []
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while quote:
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item, quote = quote
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temp.append(item)
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for item in reversed(temp):
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expression = item, expression
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return expression
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def get_n_items(n, stack):
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'''
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Return items and remainder of stack.
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Raise StackUnderflowError if there are fewer than n items on the stack.
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'''
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assert n > 0, repr(n)
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temp = []
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while n > 0:
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n -= 1
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try:
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item, stack = stack
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except ValueError:
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raise StackUnderflowError('Not enough values on stack.') from None
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temp.append(item)
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temp.append(stack)
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return tuple(temp)
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def reversed_stack(stack):
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'''
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Return list_reverseiterator object for a stack.
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'''
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return reversed(list(iter_stack(stack)))
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'''
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██████╗ ██████╗ ██╗███╗ ██╗████████╗███████╗██████╗
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██╔══██╗██╔══██╗██║████╗ ██║╚══██╔══╝██╔════╝██╔══██╗
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