1 changed files with 180 additions and 0 deletions
@ -0,0 +1,180 @@ |
|||||||
|
+++ |
||||||
|
title = "Realm of Racket: Lean to Program, One Game at a Time!" |
||||||
|
date = 2020-12-18 |
||||||
|
|
||||||
|
[taxonomies] |
||||||
|
tags = ["books", "reviews", "it", "racket", "2020 challenge", "2 stars"] |
||||||
|
+++ |
||||||
|
|
||||||
|
[GoodReads Summary](https://www.goodreads.com/book/show/17153511-realm-of-racket): |
||||||
|
Racket is a descendant of Lisp, a programming |
||||||
|
language renowned for its elegance, power, and challenging learning |
||||||
|
curve. But while Racket retains the functional goodness of Lisp, it |
||||||
|
was designed with beginning programmers in mind. Realm of Racket is |
||||||
|
your introduction to the Racket language. |
||||||
|
|
||||||
|
<!-- more --> |
||||||
|
|
||||||
|
{{ stars(stars=2) }} |
||||||
|
|
||||||
|
This is a weird book. Not because its content, or the topic at hand, |
||||||
|
but the path chosen to explain things. For example, even after reading |
||||||
|
the whole book, I don't have any idea why I should pick Racket over |
||||||
|
any other Lisp variant. |
||||||
|
|
||||||
|
So, laundry list of things that put me off: |
||||||
|
|
||||||
|
- No real explanation on why I should pick Racket over any other Lisp |
||||||
|
(or any other language, for that matter); they don't say it's faster, |
||||||
|
or more accurate, or it's syntax makes you write less bugs or the |
||||||
|
compiler will prevent you from doing it so. |
||||||
|
|
||||||
|
- There is a strong favouritism for Racket. It isn't that unexpected, |
||||||
|
but they authors start by bashing other languages, which gives a |
||||||
|
feeling that they just want to make their favourite language look |
||||||
|
better (this goes away only in the last chapter, when comparing Racket |
||||||
|
to Java). |
||||||
|
|
||||||
|
- They use different words for common things. There isn't and IDE, it |
||||||
|
is a PDE, "program development environment"; the integrated |
||||||
|
development environment becomes "interactive development |
||||||
|
environment"; functions don't "receive" parameters, they "consume" |
||||||
|
the values, which make it sound more like a Rust thing, in which the |
||||||
|
function gets the ownership of the value and, on its end, the memory |
||||||
|
is freed, which doesn't happen in Racket. |
||||||
|
|
||||||
|
- There is a bunch of "trivial", "simple", and such. This is bad, |
||||||
|
specially if you want newbies to read the book; if they don't grasp |
||||||
|
the concept, saying it is "trivial" will make them feel bad about |
||||||
|
themselves. |
||||||
|
|
||||||
|
- A lot of explanations are basically "(+ a 1)" -> "adds 1 to |
||||||
|
a". Sure, one may not understand all the facets of the code, but |
||||||
|
when you explain "why" you wrote code that way instead of "what" the |
||||||
|
code is, it is a lot easier to understand. |
||||||
|
|
||||||
|
- Because the book is too focused on explaining one single library, |
||||||
|
some things feel like "if everything you have is a hammer". For |
||||||
|
example, there is one game of attacking monsters and which the |
||||||
|
authors put the target in the state, and it doesn't feel like this |
||||||
|
should be part of the state of the game. Sure, the selected target |
||||||
|
affects the state, but it is not part of the state, at least for me, |
||||||
|
and there isn't any good explanation on why it should be part of it. |
||||||
|
|
||||||
|
- Another example uses a complex number to represent points in a 2D |
||||||
|
plane. Sure, 2D points and complex numbers are composed by two |
||||||
|
elements, but that doesn't mean that 2D points **are** complex |
||||||
|
numbers. Types matter, even in dynamic languages. |
||||||
|
|
||||||
|
So... yeah, I think I learn a bit of Racket, but I still don't know |
||||||
|
why I should pick it over anything else. Is it just the game building |
||||||
|
library? Should one pick a language exclusively because of some built |
||||||
|
in library? Doesn't anything else affects this decision? (All |
||||||
|
questions are rhetorical, it is obvious that you shouldn't pick a |
||||||
|
language just because one library). |
||||||
|
|
||||||
|
--- |
||||||
|
|
||||||
|
Highlights: |
||||||
|
|
||||||
|
> `(foo)*g++.baz(!&qux::zip->ding());` |
||||||
|
|
||||||
|
"Let me write a very contrived example, just to make my favourite |
||||||
|
language look better compared to this one." |
||||||
|
|
||||||
|
> `(sqrt (+ (sqr 3) (sqr 4)))` |
||||||
|
|
||||||
|
This is nowhere _near_ the example in C++. If you want to compare |
||||||
|
languages, at least write the same thing. |
||||||
|
|
||||||
|
> If you’re on a *nix box, you are already a hero and don’t need instructions. |
||||||
|
|
||||||
|
What a load of bull. It sounds more like you don't have an idea on how |
||||||
|
to do it in Linux. |
||||||
|
|
||||||
|
> (the compiler) DrRacket reads this expression, evaluates it, |
||||||
|
> prints the result, and then displays its prompt again. |
||||||
|
|
||||||
|
You just described an interpreter, not a compiler. For all purposes |
||||||
|
and intents, sure, it compiles the code to make sure it is not |
||||||
|
invalid, but the concept of "compiler" is used mostly for things that |
||||||
|
take a source and produce a stand-alone executable. Otherwise, even |
||||||
|
Python have a compiler. |
||||||
|
|
||||||
|
> the function uses a set! expression to change the value of a |
||||||
|
> variable. |
||||||
|
|
||||||
|
Why `set!`? Why not just `set`? What the `!` means? Nothing? Is it |
||||||
|
just a convention? |
||||||
|
|
||||||
|
> Racket has three kinds of comments |
||||||
|
|
||||||
|
And absolutely no example of those kinds. |
||||||
|
|
||||||
|
> ``` |
||||||
|
> (/ 4 6) |
||||||
|
> 2/3``` |
||||||
|
|
||||||
|
This is one cool thing: Racket keeps the values in their fractional |
||||||
|
format. |
||||||
|
|
||||||
|
> ```(struct student (name id# dorm)) |
||||||
|
> (student-name freshman1) |
||||||
|
> 'Joe |
||||||
|
> (student-id# freshman1) |
||||||
|
> 1234``` |
||||||
|
|
||||||
|
Creating structs and extracting values from them. |
||||||
|
|
||||||
|
> ```(define x 7) |
||||||
|
> (cond [(= x 7) 5] |
||||||
|
> [(odd? x) 'odd-number] |
||||||
|
> [else 'even-number])``` |
||||||
|
|
||||||
|
Multiple tests. Also, there is this use of brackets ("[") and |
||||||
|
parenthesis ("(") which is never properly explained, though. |
||||||
|
|
||||||
|
> ``` |
||||||
|
> (when (and file-modified (ask-user-about-saving)) (save-file)) |
||||||
|
> ``` |
||||||
|
|
||||||
|
Because `and` and `or` return the value if it's not the boolean false |
||||||
|
(`#f`), you can use tests to simplify the code. |
||||||
|
|
||||||
|
> ``` |
||||||
|
> (define filename "my-first-program.rkt") |
||||||
|
> (unless (ask-user-whether-to-keep-file filename) (delete-file filename)) |
||||||
|
> ``` |
||||||
|
|
||||||
|
`unless` is a form of `if` that performs an action only if the value |
||||||
|
is `#f` (false). |
||||||
|
|
||||||
|
> ``` |
||||||
|
> (struct orc monster (club)) |
||||||
|
> (struct hydra monster ()) |
||||||
|
> (struct slime monster (sliminess)) |
||||||
|
> (struct brigand monster ()) |
||||||
|
> ``` |
||||||
|
|
||||||
|
Examples of deriving structs from other structs. |
||||||
|
|
||||||
|
> In summary, mutators make programming complex |
||||||
|
|
||||||
|
Just a few paragraphs better, you used a mutator saying that this |
||||||
|
would make the code better. |
||||||
|
|
||||||
|
> `raco exe -l hello-world.rkt` |
||||||
|
|
||||||
|
Generating a standalone executable from Racket source code. |
||||||
|
|
||||||
|
> ``` |
||||||
|
> (define snake% |
||||||
|
> (class object% |
||||||
|
> (super-new) |
||||||
|
> (init-field dir head tail) |
||||||
|
> (define/public (slither) |
||||||
|
> (set! tail (cons head (all-but-last tail))) |
||||||
|
> (set! head (next-head))) |
||||||
|
> ``` |
||||||
|
|
||||||
|
Classes in Racket. |
||||||
Loading…
Reference in new issue