Week 20140406

Dan Grossman

• functions over lists are usually recursive: empty list; non-empty list (hd, tl)
• let expression: let...in...end
• Do a recursive computation, store in (local binding)
• Option: isSome, valOf
• Bool comparisons: andalso, orelse, not
• real is not an equality type (subject to round errors)
• no mutation --> no need to worry about alias or copies --> implementation more efficient & better security
• Done HW1

Brandon Rhodes Pycon talk

• Gustavo Duarte -- what your computer does while you wait
• Dan Luu -- how misaligning data can increase performance 12x
• Python store general purpose data structures (eg. tuple) as array of addresses
• append on a list adds extra spaces -- amortization
• list is fast for tail operations: append, pop. Not pop(0), insert(0)
• dict is an array with keys stored at integer indexes according to hash value:
  • hash -- key address -- value address
  • PyCon 2010 "The mighty dictionary"
  • can build compound keys with tuple
• set: dictionary with no keys
• deque, heapq
• 2013 PyCon, the clean architecture in Python

Miscellaneous

• rescue time is a neat productivity tool.