Notes from Thursday Tutoring Session

• Once a week, my mentor and I sit down and have dinner, and talk about parsers, compilers, and programming language theory.

This was from our first session

• He’s explaining parsers and recursive descent to me.

• Also, LL-1 vs LL-0 parsing.

I started thinking about Python

• One of the things that has fascinated me is trying to understand what a plus sign is to a compiler. What does it mean, and how does it know hierarchy.

• It makes sense for the hierarchy to represent it as a graph structure. But it’s really quite interesting; concepts like LL-1 and LL-0 parsers, their complexity and efficiency.

Things I learned about

• fixed point iteration (calcuating nullable)
• NDFA to DFA (removing epsilon transitions)
• sentential form (not yet a sentence..like a phrase)
• tokens
• abstract syntax trees
• recursive descent
• LL vs LR parsers
• epsilon vs lambda transitions
• “chickenfoot” (independent of in mathematical notation)
• expression vs expression follows (peek operation)

I found some resources online

• They Python documentation actually contains Lexical analysis documentation. I didn’t know that until today.

• This is from a college course. It’s from the University of Utah.

  I love this

  Few programmers will ever work on a production compiler,
  but knowing how compilers think is an asset.
  
  It makes you a better programmer.
  

Also a wonderful Paul Graham article

• This stuck out today for me

 ...I'll call the Python paradox; 
 if a company chooses to write its
 software in a comparatively 
 esoteric language, they'll be able 
 to hire better programmers,
 because they'll attract only those who cared 
 enough to learn it....
 for programmers...if you want to get a good
 job..the language to learn is a language that people 
 don't learn merely to get a job.

Read the entire article here

• I completely agree with this! It just makes sense to me, and I have to say the smartest, most passionate people I’ve met are people who have learned some interesting language, or built something interesting, or they taught themselves a language because they were really interested and curious and passionate about programming.

I’m still stoked

• I’m excited about the LinkedIn opportunity. I was reading a question on Quora today, where someone answered that life really “unfolds”. That’s very much been the case in my life, and for that, I’m thankful.

For the week

• Tomorrow, I’m going to a Sailing club. I officially joined a sailing group for women.

• I also have class on Wednesday, and hang out with my mentor (for a tutoring session) on Thursday evening.

Interesting solution to a kata

• Unnamed user solved a kata to make a letter uppercase by this

char makeupper(char letter) {
  return letter & ~('a' ^ 'A');
}

• This is very interesting! Is it dereferencing the original value, ‘a’, setting it to the new value ‘A’, and referencing the value?

• update Apparently…^ is an XOR. Ah.

Katas

• An array is inertial if :
  • there are odd values
  • the max value is even
  • every value of odd is more than even values in array

function isInertial(array){
  evenarr = []
  oddarr = []
  
  var odd = 0 // find out how many odds
  var even = Math.max.apply(null, array); // get max value
  var greater = 0 
  
  // loop through, get odds
  for (var i = 0; i < array.length; i++){
    if (array[i] % 2 !== 0){
      odd = odd + 1
    }
    if ((array[i] % 2 === 0) && (array[i] !== even)) {
      evenarr.push(array[i])
    }
    if (array[i] % 2 !== 0 ){
      oddarr.push(array[i])
    }
  }
  // get min odd value in odds array
  var minodd = Math.min.apply(null, oddarr)
  
  // check if every element in even array is less than minodd
  function  isEvery(i, index, array){
    return i < minodd
  }
  var a = evenarr.every(isEvery)
  
  // if all three satisfied, array is inertial
  if ((odd > 0) && (even % 2 === 0) && (a == true)){
    return(true)
  }
  else{
    return(false)
  }
  
  // for every value of odd, make sure larger than even arr 
  // output if true for 
  //1. odd > 0 = true 
  //2. max value is even = true 
  // every value of odd is more than even values in arr 
  
  return 
}

• if any factor of a number is even, return false. If the input is less than 1, also return false.

function isNormal(n){
 // tis so cute `^(~_~)^`
 var arr = []
 // case where n is less than 1
 if (n < 1){
   return false
 }
 else{
 // loop through to find all even factors
 // push to array
   for (var i = 2; i < n; i++){
     if ((n % i === 0) && (i % 2 !== 0)){
       arr.push(i)
     }
   }
   // if array is empty, return true
   if (arr.length === 0){
     return(true)
   }
   else{
     return(false)
   }
   return
  }
}

Things to be done…

• Version 1.1 of my C++ programme

• Data Analysis and finish up Nanodegree

• And..that’s about it!