See a typo? Have a suggestion? Edit this page on Github
I didn’t expect to be writing the second blog post only 12 hours after the first. But when the kids came downstairs this morning, they were unbelievably excited to do more coding. So here we are!
Eliezer and I discussed using more visual tooling (like Code World or Jupiter) for doing the learning, and I showed him what it looked like. It seems he’s got quite a bit of his father’s preferences, and wanted to stick to plain text for now. We’ll probably circle back to that kind of stuff after they get the basics. It will also give me a chance to get more comfortable with those offerings. (Thanks all for the recommendations on Reddit.)
One final note. I’m extremely happy that we went with Haskell after today’s lessons. Concepts like variable replacement which are natural in Haskell were great teaching tools. I obviously don’t have enough data to prove this yet, but I’m more strongly believing the long-held theory that Haskell is easier for brand new programmers than those familiar with imperative programming.
I moved us over to VSCode, with only syntax highlighting set up. Previously,
I’d used my emacs setup with intero, and the red squiggles let them know they’d
messed up too early. I used the docked terminal at the bottom, taught them to
save, and showed them to press “up enter” in the terminal to rerun
stack runghc foo.hs. Perhaps not the ideal setup, but definitely good enough.
main = print "hello world"
main is defined as other thing
main = print hello hello = "hello world"
They were not surprised at all that this just worked
hello = 5 + 6, both got confused about whether it would print
5 + 6, reminded them of strings
hello = five + six?
Both agreed it wouldn’t work. I typed in
five = 5, and ask if it would
work. They agree that it won’t, and I show them GHC’s error message.
“Variable not in scope.” Computers talk funny, just means “I don’t know what six is.” Instilled that they’ll eventually be able to understand those massive error messages, but not to worry about it yet.
Exercise: five the program. Both of them got it no problem.
I was about to demonstrate
five = 4, and then Gavriella figured it out for
herself! They understand that, again, “computers are dumb.” Names are just
there for our benefit, computer doesn’t care.
five + six * seven (with appropriate variable definitions), they get
that answer, and then
(five + six) * seven, they get that too.
Now I define
fivePlusSix = five + six, and change to
hello = (fivePlusSix) * seven
(direct replacement). They’re fine with this. Yay replacement.
Point out that the parens are now unneeded and remove them. Again, no problem.
Parens just tell us “do this first”, not needed for one thing
hello = 5 * 2, no problem.
hello = double 5? They figured out that it won’t work cuz computers be dumb
double? Eliezer guessed
* 2, which is really close, but we’re not ready for sections, and I want to teach standard function stuff first.
double x = x * 2, that
xis a variable, and a function argument. They don’t know algebra yet, but got this fairly quickly.
hello = addFive (double 5)
addFive, and he started spacing things like me without any prompting. Cool.
main, oh, I got an action! I need to print
hello, what’s that? Oh, it’s
addFive .... That means I gotta figure out
double 5? Oh, it’s
10. So that’s
minusTwowas never (terminology break, I taught them that it wasn’t used).
minusTwois also a function. It needs one number. Let’s try something wrong:
minusTwo addFive (double 5). That’s wrong: it means “apply
minusTwoto two values” but it only needs one number.
addFive (double 5)into one thing. Ask them what we can use. They played with idea of double quotes, and then they figured out the parens! Awesome!
minusTen. She did it.
Gavriella kept playing with the code (wow, she’s focused on this). She decided
she wanted to do division. That was more complicated, but she persevered. I
taught her about
div being a function that takes 2 arguments. She didn’t know
anything about remainders, and was confused that
div 15 2 worked at all. I
taught her about
divMod, and she did great.