4 ms·

The Language of Choice

94 points by pyb 11y ago

falcolas 11y ago
The code out of GitHub doesn't appear to work, at least not how you'd hope it would. Couldn't follow the article from the command line without writing the code myself. ~/src/github.com/darius/mccarthy-to-bryant (master)$ python >>> from nway_logic import * >>> A, B = Variable('A'), Variable('B') >>> A A >>> B B >>> const0 = Constant(0) Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'Constant' is not defined ~/src/github.com/darius/mccarthy-to-bryant (master)$ python Python 2.7.10 (default, Jul 13 2015, 12:05:58) [GCC 4.2.1 Compatible Apple LLVM 6.1.0 (clang-602.0.53)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> from dd import * >>> A, B = Variable('A'), Variable('B') Traceback (most recent call last): File "<stdin>", line 1, in <module> File "dd.py", line 27, in Variable return build_node(rank, tuple(map(Constant, range(arity)))) File "utils.py", line 7, in memoized result = memoized._memos[args] = f(*args) File "dd.py", line 34, in __init__ for b in branches: assert rank < b.rank AssertionError >>>
- Cogito 11y ago
  I haven't yet tried this myself, but these classes get defined just a bit further down. You might need to move them up or something in order to get the early examples to work.
- abecedarius 11y ago
  For the first, the README says it's logic.py and not nway_logic.py that has the article's code. (The latter is a generalization that was actually written first.) logic.py was extracted from the text, and the transcript tested against it. I've just backported the renaming to Constant into nway_logic, and that example should work unaltered now -- thanks! For the second, the interface to the decision diagrams does not use variables with names, as explained under 'Systematic succinctness' and demoed in make_alu_inputs() -- I aimed for the simplest code that shows the ideas. But I think you're right that bdd.Variable should've been called something different from logic.Variable.
  - falcolas 11y ago
    logic.py did not exist in my checkout, which is why I ended up trying nway_logic instead.
    - abecedarius 11y ago
      Ah, I'm sorry about that. Product of sadly declining ambitions: first for SVG toys, which I'm incompetent at; then yesterday I was looking into converting the text into an iPython notebook to provide an easier way to interact with the code, and that turned out to be too hard under the deadline. I ended up pushing the article's code into this repo shortly after the article went live.
      - falcolas 11y ago
        No problem, thanks for fixing it. I'll be diving back into the article with the code, since it makes for some really interesting reading.
        abecedarius 11y ago
        Thanks, and hope you like it!
thoastbrot 11y ago
How could he write that article without a sole mention of prolog?
- abecedarius 11y ago
  Author here. I like Prolog, and you might enjoy my https://github.com/darius/pythological https://github.com/darius/pythological. Here's an excellent free book: http://www.mtome.com/Publications/PNLA/prolog-digital.pdf http://www.mtome.com/Publications/PNLA/prolog-digital.pdf But the first draft of the article was already stuffed too full without even trying to go past propositional logic; it had to be cut, not expanded.

94 points by pyb 11y ago

The code out of GitHub doesn't appear to work, at least not how you'd hope it would. Couldn't follow the article from the command line without writing the code myself. ~/src/github.com/darius/mccarthy-to-bryant (master)$ python >>> from nway_logic import * >>> A, B = Variable('A'), Variable('B') >>> A A >>> B B >>> const0 = Constant(0) Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'Constant' is not defined ~/src/github.com/darius/mccarthy-to-bryant (master)$ python Python 2.7.10 (default, Jul 13 2015, 12:05:58) [GCC 4.2.1 Compatible Apple LLVM 6.1.0 (clang-602.0.53)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> from dd import * >>> A, B = Variable('A'), Variable('B') Traceback (most recent call last): File "<stdin>", line 1, in <module> File "dd.py", line 27, in Variable return build_node(rank, tuple(map(Constant, range(arity)))) File "utils.py", line 7, in memoized result = memoized._memos[args] = f(*args) File "dd.py", line 34, in __init__ for b in branches: assert rank < b.rank AssertionError >>>

Cogito 11y ago
I haven't yet tried this myself, but these classes get defined just a bit further down. You might need to move them up or something in order to get the early examples to work.
abecedarius 11y ago
For the first, the README says it's logic.py and not nway_logic.py that has the article's code. (The latter is a generalization that was actually written first.) logic.py was extracted from the text, and the transcript tested against it. I've just backported the renaming to Constant into nway_logic, and that example should work unaltered now -- thanks! For the second, the interface to the decision diagrams does not use variables with names, as explained under 'Systematic succinctness' and demoed in make_alu_inputs() -- I aimed for the simplest code that shows the ideas. But I think you're right that bdd.Variable should've been called something different from logic.Variable.
- falcolas 11y ago
  logic.py did not exist in my checkout, which is why I ended up trying nway_logic instead.
  - abecedarius 11y ago
    Ah, I'm sorry about that. Product of sadly declining ambitions: first for SVG toys, which I'm incompetent at; then yesterday I was looking into converting the text into an iPython notebook to provide an easier way to interact with the code, and that turned out to be too hard under the deadline. I ended up pushing the article's code into this repo shortly after the article went live.
    - falcolas 11y ago
      No problem, thanks for fixing it. I'll be diving back into the article with the code, since it makes for some really interesting reading.
      - abecedarius 11y ago
        Thanks, and hope you like it!

thoastbrot 11y ago

How could he write that article without a sole mention of prolog?

abecedarius 11y ago
Author here. I like Prolog, and you might enjoy my https://github.com/darius/pythological https://github.com/darius/pythological. Here's an excellent free book: http://www.mtome.com/Publications/PNLA/prolog-digital.pdf http://www.mtome.com/Publications/PNLA/prolog-digital.pdf But the first draft of the article was already stuffed too full without even trying to go past propositional logic; it had to be cut, not expanded.