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+++
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title = "Introducing Erlang: Getting Started in Functional Programming - Simon St. Laurent"
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date = 2020-08-05
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updated = 2020-10-26
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[taxonomies]
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tags = ["books", "reviews", "simon st laurent", "erlang", "it",
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"books:2020", "2 stars"]
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+++
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[GoodReads Summary](https://www.goodreads.com/book/show/15811999-introducing-erlang):
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If you’re new to Erlang, its functional style can seem difficult, but with
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help from this hands-on introduction, you’ll scale the learning curve and
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discover how enjoyable, powerful, and fun this language can be.
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<!-- more -->
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{{ stars(stars=2) }}
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Again, an "Introducing" book that one shouldn't expect some deep explanations,
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but heck, this felt shallower than [Introducing
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Elixir](@/reviews/books/introducing-elixir.md).
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It follows the same path of the "Introducing Elixir" (or maybe it is the other
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way around, but hey, that's the order I read both), by creating a "what speed
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will something crash if dropped in different planets" library and exploring
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changes.
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But the biggest drawback is that the book sticks too much into the Erlang
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Shell and absolutely nothing (besides "here is one thing you can search for")
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outside it. I mean, sure, the language may be nice and fun and all that, but
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what's the point if the build tool is a pain and dependency resolution is
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inexistent -- and I'm not saying Erlang suffers from that, 'cause as a
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learning path, the book says _nothing_ about those things.
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For seeing how the language looks like, it's a good book. For something more
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_real_... far away from it.
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## Highlights
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> go to the command line and type erl
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*Note*: `erl` is the Erlang Shell.
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> 3> 2#1010111.
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*Note*: Binary notation.
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> 4> 16#cafe
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*Note*: Hex notation.
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> FallVelocity = fun(Distance) -> math:sqrt(2 * 9.8 * Distance) end.
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*Note*: `fun` creates an anonymous function; it is then associated with the
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name `FallVelocity` (all variables need to start with an upcase letter).
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> -module(drop).<br>
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> -export([fall_velocity/1, mps_to_mph/1, mps_to_kph/1]).<br><br>
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> fall_velocity(Distance) -> math:sqrt(2 * 9.8 * Distance). <br>
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> mps_to_mph(Mps) -> 2.23693629 * Mps.<br>
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> mps_to_kph(Mps) -> 3.6 * Mps.
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> -module(combined).<br>
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> -export([height_to_mph/1]).<br>
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> -import(drop, [fall_velocity/1]).<br>
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> -import(convert, [mps_to_mph/1]).<br>
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> height_to_mph(Meters) -> mps_to_mph(fall_velocity(Meters)).
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> In Erlang, greater-than-or-equal-to is written as >=, and
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> less-than-or-equal-to as =<. Don’t make them look like arrows.
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> try <br>
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> math:sqrt(2 * Gravity * Distance) <br>
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> catch <br>
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> error:Error -> {error, Error} end.
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> Creating a map requires a different syntax presenting keys and values:<br>
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> 1> Planemos = #{ earth => 9.8, moon => 1.6, mars => 3.71 }.<br>
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> #{earth => 9.8,mars => 3.71,moon => 1.6}
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