Week 20140504

Dan Grossman

  • Syntax, semantics, idioms, libraries, tools
  • records: #field_name record_name
  • tuples are syntax sugers of records (field_name = 1, 2, 3...)
  • datatype bindings: Constant of int | Add of expr * expr
  • pattern matching: case x of =>
  • one-of (Option); each-of (Records)
  • type synonym: type name = t. type card = suit * rank
  • polymorphic datatype: datatype 'a option = NONE | SOME of 'a
  • val p = e. p --> patterns
  • fun f p = e
  • exception, raise
  • e1 handle exn => e2
  • tail optimization: remove caller from call stack
  • the wrath of premature optimization

Foundation by Isaac Asimov

(Notes generated by my little Kindle script

  • If you're born in a cubicle and grow up in a corridor, and work in a cell, and vacation in a crowded sun-room, then coming up into the open with nothing but sky over you might just give you a nervous breakdown.
  • I don't care an electron
  • And when Onum Barr stepped into his little garden early the next morning, he found a box at his feet. It contained provisions, concentrated provisions such as one would find aboard ship, and alien in taste and preparation. But they were good, and lasted long.
  • The whole war is a battle between those two systems, between the Empire and the Foundation; between the big and the little.

Max sub-array problem

def max_sub_array(l):
    max_ending_here = max_so_far = l[0]
    begin = begin_temp = end = l[0]

    for i in range(1, len(l)):
        if l[i] > l[i] + max_ending_here:
            max_ending_here = l[i]
            begin_temp = i
            max_ending_here += l[i]

        if max_ending_here >= max_so_far:
            max_so_far = max_ending_here
            begin = begin_temp
            end = i

    return max_so_far, begin, end


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