For anyone having trouble with the Monoid instance, things have changed with Monoids & Semigroups in base since 4.11. You can try changing the "instance Monoid Report where" section to: instance Semigroup Report where (Report b1 a1 d1) (Report b2 a2 d2) = Report (b1 + b2) (a1 + a2) (d1 + d2) instance Monoid Report where mempty = Report 0 0 0
Missing from the video voice-over, but included in the show notes, is this disclaimer which I want to stress: "The use of Double for modelling money is not well-suited for real systems, and should be replaced with a proper arbitrary-precision data type, e.g. Scientific. In the spirit of keeping down the scope of this tutorial Double was still used."
Got an error for the Money type. No instance for (Eq Money) gist.github.com/streamerd/f24e5b91b687361e88363f11aa9ef591 code I am using: gist.github.com/streamerd/0de4b16b2c9b308914d09e892d61fa7a
Do people often write concrete types and then refactor to more polymorphic versions in Haskell programming, like what you have shown in your tutorials?
Haskell Type I can't answer for people in general, but I often do just that. I might write a specialized function, see what type GHC infers, and then use that. Things like functors and traversable might require some more experience to identify on your own, but you'll see the patterns once you start working with these things regularly.
What does `Money` do that regular numbers couldn’t do? How is doing this with types different (better, hopefully) than doing it with objects? What does [stockholm, gothenburg, malmø] accomplish? It looks like you just type the same word with different "", [], and capitalization in various places. Sorry, I find this confusing.
When you spend years to perfect writing readable code.... you read this: "newType Money = Money { unMoney :: Double } deriving {Show, Eq, Num}" Money = Money eh? Very profound...Nah. This is unreadable garbage. Hehe...even IT-nerds think those math kids are weird eh?
left Money is a type name, right Money is a ctor name. If you are this supposed proper "IT nerd" maybe the following example of C++ "using iipair = pair;" would put you off too?
For anyone having trouble with the Monoid instance, things have changed with Monoids & Semigroups in base since 4.11.
You can try changing the "instance Monoid Report where" section to:
instance Semigroup Report where
(Report b1 a1 d1) (Report b2 a2 d2) =
Report (b1 + b2) (a1 + a2) (d1 + d2)
instance Monoid Report where
mempty = Report 0 0 0
Great presentation, please keep it coming
The intro sounds like a Law & Order intro. So serious!
Haskell is law and order. Haskell is serious. :)
Font is Iosevka Term AFAIK if anyone's wondering, beautiful
thanks a lot bro
Thank you for the video series. Keep on doing the awesome work.
Missing from the video voice-over, but included in the show notes, is this disclaimer which I want to stress: "The use of Double for modelling money is not well-suited for real systems, and should be replaced with a proper arbitrary-precision data type, e.g. Scientific. In the spirit of keeping down the scope of this tutorial Double was still used."
I was just going to quibble! (Maybe add a text box annotation over the video?)
Vilem-Benjamin Liepelt TH-cam doesn't support it anymore :/
Oh noes, what a drag. Never mind, it's great as it is.
Great presentation with a good example. Thank you!
Got an error for the Money type.
No instance for (Eq Money)
gist.github.com/streamerd/f24e5b91b687361e88363f11aa9ef591
code I am using:
gist.github.com/streamerd/0de4b16b2c9b308914d09e892d61fa7a
Thanks for the effort! Can't wait to watch the next one :)
Great video. You have a new fan, keep it coming.
Can you make a video on you editor configuration? They would be a better way for some to start over.
Please, give us more of those videos.
Superb content!
How do you deal with repeating field names accross the data definitions? Eg a Person can have a name, so can an Animal
Haskell would normally not let me compile this
Woah! How do you open REPL from Vim?
In this video I was using intero-neovim, which integrates the intero/GHCi REPL with Neovim .
At 1:59 and 9:53 you format the layout automatically. How are you doing this?
I'm using hindent through Neoformat. More info in the FAQ: haskell-at-work.com/about.html#what-editor-are-you-using
What is your font?
What the theme of you text editor?
KDeveloper vim-one: github.com/rakr/vim-one
Is this vim?
Do people often write concrete types and then refactor to more polymorphic versions in Haskell programming, like what you have shown in your tutorials?
Haskell Type I can't answer for people in general, but I often do just that. I might write a specialized function, see what type GHC infers, and then use that. Things like functors and traversable might require some more experience to identify on your own, but you'll see the patterns once you start working with these things regularly.
What does `Money` do that regular numbers couldn’t do? How is doing this with types different (better, hopefully) than doing it with objects?
What does [stockholm, gothenburg, malmø] accomplish? It looks like you just type the same word with different "", [], and capitalization in various places.
Sorry, I find this confusing.
When you spend years to perfect writing readable code....
you read this:
"newType Money = Money
{ unMoney :: Double
} deriving {Show, Eq, Num}"
Money = Money eh? Very profound...Nah. This is unreadable garbage.
Hehe...even IT-nerds think those math kids are weird eh?
left Money is a type name, right Money is a ctor name. If you are this supposed proper "IT nerd" maybe the following example of C++ "using iipair = pair;" would put you off too?