From 938f49fc7835501192ccc7db7c1ab3174f050b34 Mon Sep 17 00:00:00 2001 From: Louis Pilfold Date: Tue, 20 Feb 2024 12:20:16 +0000 Subject: Let assert --- .../lesson04_externals/code.gleam | 17 --------------- .../lesson04_externals/en.html | 25 ---------------------- 2 files changed, 42 deletions(-) delete mode 100644 src/content/chapter5_advanced_features/lesson04_externals/code.gleam delete mode 100644 src/content/chapter5_advanced_features/lesson04_externals/en.html (limited to 'src/content/chapter5_advanced_features/lesson04_externals') diff --git a/src/content/chapter5_advanced_features/lesson04_externals/code.gleam b/src/content/chapter5_advanced_features/lesson04_externals/code.gleam deleted file mode 100644 index 1101b82..0000000 --- a/src/content/chapter5_advanced_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: -// export function now() { -// return new Date(); -// } - -pub fn main() { - io.debug(now()) -} diff --git a/src/content/chapter5_advanced_features/lesson04_externals/en.html b/src/content/chapter5_advanced_features/lesson04_externals/en.html deleted file mode 100644 index 8815fa7..0000000 --- a/src/content/chapter5_advanced_features/lesson04_externals/en.html +++ /dev/null @@ -1,25 +0,0 @@ -

- 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 external functions and external types allow us to - import and use this non-Gleam code. -

-

- An external type is one that has no constructors. Gleam doesn't know what - shape it has or how to create one, it only knows that it exists. -

-

- An external function is one that has the @external attribute on - it, directing the compiler to use the specified module function as the - implementation, instead of Gleam code. -

-

- 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! -

-

- External functions are useful but should be used sparingly. Prefer to write - Gleam code where possible. -

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