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Diffstat (limited to 'src/content/chapter5_advance_features')
14 files changed, 0 insertions, 282 deletions
diff --git a/src/content/chapter5_advance_features/lesson00_use/code.gleam b/src/content/chapter5_advance_features/lesson00_use/code.gleam deleted file mode 100644 index 37624ab..0000000 --- a/src/content/chapter5_advance_features/lesson00_use/code.gleam +++ /dev/null @@ -1,38 +0,0 @@ -import gleam/io -import gleam/result - -pub fn main() { - io.debug(without_use()) - io.debug(with_use()) -} - -pub fn without_use() { - result.try(get_usename(), fn(username) { - result.try(get_password(), fn(password) { - result.map(log_in(username, password), fn(greeting) { - greeting <> ", " <> username - }) - }) - }) -} - -pub fn with_use() { - use username <- result.try(get_usename()) - use password <- result.try(get_password()) - use greeting <- result.map(log_in(username, password)) - greeting <> ", " <> username -} - -// Here are some pretend functions for this example: - -fn get_usename() { - Ok("alice") -} - -fn get_password() { - Ok("hunter2") -} - -fn log_in(_username: String, _password: String) { - Ok("Welcome") -} diff --git a/src/content/chapter5_advance_features/lesson00_use/text.html b/src/content/chapter5_advance_features/lesson00_use/text.html deleted file mode 100644 index e295dda..0000000 --- a/src/content/chapter5_advance_features/lesson00_use/text.html +++ /dev/null @@ -1,31 +0,0 @@ -<p> - Gleam lacks exceptions, macros, type classes, early returns, and a variety of - other features, instead going all-in with just first-class-functions and - pattern matching. This makes Gleam code easier to understand, but it can - sometimes result in excessive indentation. -</p> -<p> - Gleam's use expression helps out here by enabling us to write code that uses - callbacks in an unindented style, as shown in the code window. -</p> - -<p> - The higher order function being called goes on the right hand side of the - <code><-</code> operator. It must take a callback function as its final - argument. -</p> -<p> - The argument names for the callback function go on the left hand side of the - <code><-</code> operator. The function can take any number of arguments, - including zero. -</p> -<p> - All the following code in the <code class="hljs">{}</code> block becomes the - body of the callback function. -</p> -<p> - This is a very capable and useful feature, but excessive application of - <code>use</code> may result in code that is unclear otherwise, especially to - beginners. Often using the regular function call syntax will result in more - approachable code! -</p> diff --git a/src/content/chapter5_advance_features/lesson01_use_sugar/code.gleam b/src/content/chapter5_advance_features/lesson01_use_sugar/code.gleam deleted file mode 100644 index ac61062..0000000 --- a/src/content/chapter5_advance_features/lesson01_use_sugar/code.gleam +++ /dev/null @@ -1,30 +0,0 @@ -import gleam/io -import gleam/result - -pub fn main() { - let x = { - use username <- result.try(get_usename()) - use password <- result.try(get_password()) - use greeting <- result.map(log_in(username, password)) - greeting <> ", " <> username - } - - case x { - Ok(greeting) -> io.println(greeting) - Error(error) -> io.println_error(error) - } -} - -// Here are some pretend functions for this example: - -fn get_usename() { - Ok("alice") -} - -fn get_password() { - Ok("hunter2") -} - -fn log_in(_username: String, _password: String) { - Ok("Welcome") -} diff --git a/src/content/chapter5_advance_features/lesson01_use_sugar/text.html b/src/content/chapter5_advance_features/lesson01_use_sugar/text.html deleted file mode 100644 index e28c843..0000000 --- a/src/content/chapter5_advance_features/lesson01_use_sugar/text.html +++ /dev/null @@ -1,30 +0,0 @@ -<p> - The <code>use</code> expression is syntactic sugar for a regular function call - and an anonymous function. -</p> - -<p>This code:</p> -<pre> -use a, b <- my_function -next(a) -next(b) -</pre> - -<p>Expands into this code:</p> -<pre> -my_function(fn(a, b) { - next(a) - next(b) -}) -</pre> - -<p> - To ensure that your <code>use</code> code works and is as understandable as - possible, the right-hand-side ideally should be a function call rather than a - pipeline or other expression, which is typically more difficult to read. -</p> - -<p> - <code>use</code> is an expression like everything else in Gleam, so it can be - placed within blocks. -</p> diff --git a/src/content/chapter5_advance_features/lesson02_todo/code.gleam b/src/content/chapter5_advance_features/lesson02_todo/code.gleam deleted file mode 100644 index d5abe8f..0000000 --- a/src/content/chapter5_advance_features/lesson02_todo/code.gleam +++ /dev/null @@ -1,7 +0,0 @@ -pub fn main() { - todo as "I haven't written this code yet!" -} - -pub fn todo_without_reason() { - todo -} diff --git a/src/content/chapter5_advance_features/lesson02_todo/text.html b/src/content/chapter5_advance_features/lesson02_todo/text.html deleted file mode 100644 index 4a2c433..0000000 --- a/src/content/chapter5_advance_features/lesson02_todo/text.html +++ /dev/null @@ -1,14 +0,0 @@ -<p> - The <code>todo</code> keyword is used to specify that some code is not yet - implemented. -</p> -<p> - The <code>as "some string"</code> is optional, though you may wish to include - the message if you have more than one code block marked as - <code>todo</code> in your code. -</p> -<p> - When used the Gleam compiler will print a warning to remind you the code is - unfinished, and if the code is run then the program will crash with the given - message. -</p> diff --git a/src/content/chapter5_advance_features/lesson03_panic/code.gleam b/src/content/chapter5_advance_features/lesson03_panic/code.gleam deleted file mode 100644 index fce9d66..0000000 --- a/src/content/chapter5_advance_features/lesson03_panic/code.gleam +++ /dev/null @@ -1,15 +0,0 @@ -import gleam/io - -pub fn main() { - print_score(10) - print_score(100_000) - print_score(-1) -} - -pub fn print_score(score: Int) { - case score { - score if score > 1000 -> io.println("High score!") - score if score > 0 -> io.println("Still working on it") - _ -> panic as "Scores should never be negative!" - } -} diff --git a/src/content/chapter5_advance_features/lesson03_panic/text.html b/src/content/chapter5_advance_features/lesson03_panic/text.html deleted file mode 100644 index 843a65b..0000000 --- a/src/content/chapter5_advance_features/lesson03_panic/text.html +++ /dev/null @@ -1,11 +0,0 @@ -<p> - The <code>panic</code> keyword is similar to <code>todo</code> keyword, but it - is used to crash the program when the program has reached a point that should - never be reached. -</p> -<p> - This keyword should almost never be used! It may be useful in initial - prototypes and scripts, but its use in a library or production application is - a sign that the design could be improved. With well designed types the type - system can typically be used to make these invalid states unrepresentable. -</p> diff --git a/src/content/chapter5_advance_features/lesson04_externals/code.gleam b/src/content/chapter5_advance_features/lesson04_externals/code.gleam deleted file mode 100644 index ade2c54..0000000 --- a/src/content/chapter5_advance_features/lesson04_externals/code.gleam +++ /dev/null @@ -1,17 +0,0 @@ -import gleam/io - -// A type with no Gleam constructors -pub type DateTime - -// An external function that creates an instance of the type -@external(javascript, "./my_package_ffi.mjs", "now") -pub fn now() -> DateTime - -// The `now` function in `./my_package_ffi.mjs` looks like this: -// external function now() { -// return new Date(); -// } - -pub fn main() { - io.debug(now()) -} diff --git a/src/content/chapter5_advance_features/lesson04_externals/text.html b/src/content/chapter5_advance_features/lesson04_externals/text.html deleted file mode 100644 index 81202d6..0000000 --- a/src/content/chapter5_advance_features/lesson04_externals/text.html +++ /dev/null @@ -1,25 +0,0 @@ -<p> - Sometimes in our projects we want to use code written in other languages, most - commonly Erlang and JavaScript, depending on which runtime is being used. - Gleam's <em>external functions</em> and <em>external types</em> allow us to - import and use this non-Gleam code. -</p> -<p> - An external type is a one that has no constructors. Gleam doesn't know what - shape it has or how to create one, it only knows that it exists. -</p> -<p> - An external function is one that has the <code>@external</code> attribute on - it, directing the compiler to use the specified module function as the - implementation, instead of Gleam code. -</p> -<p> - The compiler can't tell the types of functions written in other languages, so - when the external attribute is given type annotations must be provided. Gleam - trusts that the type given is correct so an inaccurate type annotation can - result in unexpected behaviour and crashes at runtime. Be careful! -</p> -<p> - External functions are useful but should be used sparingly. Prefer to write - Gleam code where possible. -</p> diff --git a/src/content/chapter5_advance_features/lesson05_multi_target_externals/code.gleam b/src/content/chapter5_advance_features/lesson05_multi_target_externals/code.gleam deleted file mode 100644 index b62a735..0000000 --- a/src/content/chapter5_advance_features/lesson05_multi_target_externals/code.gleam +++ /dev/null @@ -1,11 +0,0 @@ -import gleam/io - -pub type DateTime - -@external(erlang, "calendar", "local_time") -@external(javascript, "./my_package_ffi.mjs", "now") -pub fn now() -> DateTime - -pub fn main() { - io.debug(now()) -} diff --git a/src/content/chapter5_advance_features/lesson05_multi_target_externals/text.html b/src/content/chapter5_advance_features/lesson05_multi_target_externals/text.html deleted file mode 100644 index dc10a19..0000000 --- a/src/content/chapter5_advance_features/lesson05_multi_target_externals/text.html +++ /dev/null @@ -1,22 +0,0 @@ -<p> - Multiple external implementations can be specified for the same function, - enabling the function to work on both Erlang and JavaScript. -</p> -<p> - If a function doesn't have an implementation for the currently compiled-for - target then the compiler will return an error. -</p> -<p> - You should try to implement functons for all targets, but this isn't always - possible due to incompatibilities in how IO and concurreny works in Erlang and - JavaScript. With Erlang concurrent IO is handled transparently by the runtime, - while in JavaScript concurrent IO requires the use of promises or callbacks. - If your code uses the Erlang style it is typically not possible to implement - in JavaScript, while if callbacks are used then it won't be compatible with - most Gleam and Erlang code as it forces any code that calls the function to - also use callbacks. -</p> -<p> - Libraries that make use of concurrent IO will typically have to decide whether - they support Erlang or JavaScript, and document this in their README. -</p> diff --git a/src/content/chapter5_advance_features/lesson06_external_gleam_fallbacks/code.gleam b/src/content/chapter5_advance_features/lesson06_external_gleam_fallbacks/code.gleam deleted file mode 100644 index a97b8fc..0000000 --- a/src/content/chapter5_advance_features/lesson06_external_gleam_fallbacks/code.gleam +++ /dev/null @@ -1,18 +0,0 @@ -import gleam/io - -@external(erlang, "lists", "reverse") -pub fn reverse_list(items: List(e)) -> List(e) { - tail_recursive_reverse(items, []) -} - -fn tail_recursive_reverse(items: List(e), reversed: List(e)) -> List(e) { - case items { - [] -> reversed - [first, ..rest] -> tail_recursive_reverse(rest, [first, ..reversed]) - } -} - -pub fn main() { - io.debug(reverse_list([1, 2, 3, 4, 5])) - io.debug(reverse_list(["a", "b", "c", "d", "e"])) -} diff --git a/src/content/chapter5_advance_features/lesson06_external_gleam_fallbacks/text.html b/src/content/chapter5_advance_features/lesson06_external_gleam_fallbacks/text.html deleted file mode 100644 index 243c7ea..0000000 --- a/src/content/chapter5_advance_features/lesson06_external_gleam_fallbacks/text.html +++ /dev/null @@ -1,13 +0,0 @@ -<p> - It's possible for a function to have both a Gleam implementation and an - external implementation. If there exists an external implementation for the - currently compiled-for target then it will be used, otherwise the Gleam - implementation is used. -</p> -<p> - This may be useful if you have a function that can be implemented in Gleam, - but there is an optimised implementation that can be used for one target. For - example, the Erlang virtual machine has a built-in list reverse function that - is implemented in native code. The code here uses this implementation when - running on Erlang, as it is then available. -</p> |