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Diffstat (limited to 'src/content/chapter1_functions/lesson04_generic_functions')
-rw-r--r-- | src/content/chapter1_functions/lesson04_generic_functions/code.gleam | 19 | ||||
-rw-r--r-- | src/content/chapter1_functions/lesson04_generic_functions/text.html | 25 |
2 files changed, 0 insertions, 44 deletions
diff --git a/src/content/chapter1_functions/lesson04_generic_functions/code.gleam b/src/content/chapter1_functions/lesson04_generic_functions/code.gleam deleted file mode 100644 index e232bf8..0000000 --- a/src/content/chapter1_functions/lesson04_generic_functions/code.gleam +++ /dev/null @@ -1,19 +0,0 @@ -import gleam/io - -pub fn main() { - let add_one = fn(x) { x + 1 } - let exclaim = fn(x) { x <> "!" } - - // Invalid, Int and String are not the same type - // twice(10, exclaim) - - // Here the type variable is replaced by the type Int - io.debug(twice(10, add_one)) - - // Here the type variable is replaced by the type String - io.debug(twice("Hello", exclaim)) -} - -fn twice(argument: value, function: fn(value) -> value) -> value { - function(function(argument)) -} diff --git a/src/content/chapter1_functions/lesson04_generic_functions/text.html b/src/content/chapter1_functions/lesson04_generic_functions/text.html deleted file mode 100644 index 1369c93..0000000 --- a/src/content/chapter1_functions/lesson04_generic_functions/text.html +++ /dev/null @@ -1,25 +0,0 @@ -<p> - Up until now each function has accepted precisely one type for each of its - arguments. -</p> -<p> - The <code>twice</code> function for example only worked with functions that - would take and return ints. This is overly restrictive, it should be possible - to use this function with any type, so long as the function and the initial - value are compatible. -</p> -<p> - To enable this Gleam support <em>generics</em>, also known as <em>parametric - polymorphism</em>. -</p> -<p> - This works by instead of specifying a concrete type, a type variable is used - which stands in for whatever specific type is being used when the function is - called. These type variable are written with a lowercase name. -</p> -<p> - Type variables are not like an <code>any</code> type, they get replaced with a - specific type each time the function is called. Try uncommenting - <code>twice(10, exclaim)</code> to see the compiler error from trying to use a - type variable as an int and a string at the same time. -</p> |