ww2

your title is more eye-catching in addition to more accurate.

I guess the speed of APL is comparable to python rather than Fortran?

Project Euler is a good place for teenagers to start learning programming, better than the routes of game or website design.

But LINQ is too slow comparing to vanilla SQL.

When you look at the GPS estimated time of arrival, or check the current MPG or mile left for your car.

Kalman filter is a natural example of iterative algorithm. Writing it in Fold does not gain much.

I think this is overdone and does not help the intuition. two things: (1). the first step of transposing the second matrix 90 degree is unnecessary and confusing. A row vector and a column vector are different. This step confuses the two. (2). All the final elements are independent and should be calculated in parallel, the stepped anime is not necessary and does not reveal this basic fact.

If you compose two linear transformations into one step, and apply distributive property, you get the matrix multiplication rule.

http://math.stackexchange.com/questions/31725/intuition-behi...

stock price is about the sum of all future cash flow. not current profit level. you can have different forecasts, but you cannot say the act of making forecast itself is nonsense.

I do not like it because http://stackoverflow.com/questions/18880654/why-do-i-get-sam...

"Most of the stuff is rational trivia" --- rational trivia, I like the word.

That is just the point, you dont have to limit yourself to "Pythonic". your style can be language agnostic.

try to get the derivative of sin(x) from his approach.

Definition 5.1/5.2 is interesting. It defines derivative at point c, not the derivative function of f. Note that f1(x) is not equal to f'(x) for all x, but f1(c) = f'(c).

Good point but examples can also be drawn from other fields like programming rather than from mathematics. So far I found that the link below is very enlightening. http://bartoszmilewski.com/2014/10/28/category-theory-for-pr...

Almost none of them are significant.

There is a big gap between chapter 1 and chapter 3, which makes me doubt this book is very unrealistic. In chapter 1, it argues kids cannot follow logic, it is not trivial for them to understand the counting with rearrangement; in chapter 3, they suddenly can count c(5,2), and they even can understand this number by using symbols URR.., which requires an algebraic mind.

don't be fooled by the title of the book. The content is beyond 7 year old kids in the US.

People use R as a convenient tool.i.e., R users are tool/library users, not tool builders in general. Haskell cannot compete with R for this user base.

one hurdle of J is that the verb train approach is too raw.

you missed two most important methods:

5+9 = (((((((((5+1)+1)++1)+1)+1)+1)+1)+1)+1) 5+9 = 9 + 5 =...

That is correct. Math is a language more than 'logic'/patterns'/ and any other metaphors.

Even the music metaphor is the same. And the mention of geometry proof. The blogger is so uncreative.

The example is too trivial. you could have 100 ways to write "hello world", but it does not matter.

How would a functional language compiler deal with this case? like GHC?

This is a typical pitfall of many FP code chuck examples. trading efficiency for superficial succinctness.

learning another script language is totally different from learning Haskell. For the latter it requires much more than syntax translation, which is implied in your comment.

Why Dorian would say something below? Asked if he was technically able to come up with the idea for bitcoin, Nakamoto responded: "Capability? Yes, but any programmer could do that."

"Yes, but any programmer could do that." ---- Either this Dorian is ignorant or it is his natural response. This quote is weird.

I found that APL/Q/J and vim share the same required mindset. If someone loves one, it is likely he/she will like another.

From the demo video, it seems a query language to query a database of knowledge. how's this knowledge database maintained and self updated are more interesting than the query language itself.

Name collision with Q/kdb+.