| import math | |
| ROOT5 = math.sqrt(5) | |
| PHI = (1 + ROOT5) / 2 | |
| def closed_fib(n): | |
| v = (PHI**n) / ROOT5 | |
| return int(v) |
| If you're coming from a language like or JavaScript (JS) or Python, you may | |
| used to be a mental model where functions (or lambdas) can actually have | |
| zero parameters. In those languages nothing gets evaluated until you | |
| invoke the functions. | |
| ## zero parameters | |
| Here's JS: | |
| ~~~ js |
| # ~/.bashrc: executed by bash(1) for non-login shells. | |
| # see /usr/share/doc/bash/examples/startup-files (in the package bash-doc) | |
| # for examples | |
| # If not running interactively, don't do anything | |
| case $- in | |
| *i*) ;; | |
| *) return;; | |
| esac |
| syntax on | |
| set ai et sw=4 ts=4 softtabstop=4 | |
| set number | |
| set backspace=indent,eol,start | |
| set wildmenu | |
| set wildmode=longest:full,full | |
| autocmd BufWritePre *.py :%s/\s\+$//e |
| fun hanoi(num-disks :: Number%(num-is-integer)) -> List: | |
| doc: "Solve the Towers of Hanoi puzzle" | |
| # our pegs are labeled 1, 2, and 3 | |
| # our disks are labeled 1 to num-disks, where disk 1 is | |
| # the smallest disk | |
| fun _hanoi(n, from-peg, target-peg): | |
| if n == 0: | |
| [list:] | |
| else: | |
| # The way Hanoi works is that you recursively move all |
| # This program is inspired by the following webpage: | |
| # | |
| # https://rosettacode.org/wiki/Combinations | |
| fun combos(lst :: List, size :: Number) -> List: | |
| # return all subsets of lst of a certain size, | |
| # maintaining the original ordering of the list | |
| # Let's handle a bunch of degenerate cases up front | |
| # to be defensive... |
| fun is-balanced-int-list(lst :: List, start_sum :: Number) -> Boolean: | |
| doc: | |
| "returns true iff the running sum of a list of " | |
| "integers stays nonnegative and finishes at zero." | |
| # Perhaps overly abstracting a bit, we model the balanced | |
| # parentheses problem in terms of a list of integers and | |
| # their running sum. | |
| # | |
| # For the concrete case of balancing parentheses, this effectively |
| #!/usr/bin/env python | |
| import sys | |
| import re | |
| import json | |
| def debug(obj): | |
| print(json.dumps(obj, indent=4)) | |
| def parse_file(fn): | |
| text = open(fn).read() |