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src/content/chapter3_data_types/lesson06_results/code.gleam

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+import gleam/io
+import gleam/int
+
+pub fn main() {
+  io.debug(buy_pastry(10))
+  io.debug(buy_pastry(8))
+  io.debug(buy_pastry(5))
+  io.debug(buy_pastry(3))
+}
+
+pub type Error {
+  NotEnoughMoney(required: Int)
+  NotLuckyEnough
+}
+
+fn buy_pastry(money: Int) -> Result(Int, Error) {
+  case money >= 5 {
+    True ->
+      case int.random(4) == 0 {
+        True -> Error(NotLuckyEnough)
+        False -> Ok(money - 5)
+      }
+    False -> Error(NotEnoughMoney(required: 5))
+  }
+}

src/content/chapter3_data_types/lesson06_results/text.html

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+<p>
+  Gleam doesn't use exceptions, instead computations that can either succeed or
+  fail return a value of the built-in <code>Result(value, error)</code> type. It
+  has two variants:
+</p>
+<ul>
+  <li>
+    <code>Ok</code>, which contains the return value of a successful
+    computation.
+  </li>
+  <li>
+    <code>Error</code>, which contains the reason for a failed computation.
+  </li>
+</ul>
+<p>
+  The type is generic with two type parameters, one for the success value and
+  one for the error. With these the result can hold any type for success and
+  failure.
+</p>
+<p>
+  Commonly Gleam programs and library will define custom types with a variant
+  for each possible problem that can arise, along with any error information
+  that would be useful to the programmer.
+</p>
+<p>
+  This is advantageous over exceptions as you can immediately see what if any
+  errors a function can return, and the compiler will ensure they are handled.
+  No nasty surprises with unexpected exceptions!
+</p>
+<p>
+  Result value can be handled by pattern matching with a
+  <code>case</code> expression, but given how frequently results are returned
+  this can become unwieldy. Gleam code commonly uses the
+  <code>gleam/result</code> standard library module and
+  <code>use</code> expressions when working with results, both of which will be
+  covered in later chapters.
+</p>

src/content/chapter4_standard_library/lesson00_standard_library_package/code.gleam

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+import gleam/io
+
+pub fn main() {
+  io.println("Hello, Joe!")
+  io.println("Hello, Mike!")
+}

src/content/chapter4_standard_library/lesson00_standard_library_package/text.html

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+<p>
+  The Gleam standard library is a regular Gleam package that has been published
+  to the <a href="https://hex.pm">Hex</a> package repository. You could opt to
+  not use if you wish, though almost all Gleam projects depend on it.
+</p>
+<p>
+  All of the modules imported so far in this guide, such as
+  <code>gleam/io</code>, are from the standard library.
+</p>
+<p>
+  All of the documentation for the standard library is available on
+  <a href="https://hexdocs.pm/gleam_stdlib/">HexDocs</a>. We will go over some
+  of the most commonly used modules now.
+</p>