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-rw-r--r--lessons/src/lesson025_list_patterns/code.gleam17
-rw-r--r--lessons/src/lesson025_list_patterns/text.html15
2 files changed, 32 insertions, 0 deletions
diff --git a/lessons/src/lesson025_list_patterns/code.gleam b/lessons/src/lesson025_list_patterns/code.gleam
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+++ b/lessons/src/lesson025_list_patterns/code.gleam
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+import gleam/io
+import gleam/int
+import gleam/list
+
+pub fn main() {
+ let x = list.repeat(int.random(0, 5), times: int.random(0, 3))
+ io.debug(x)
+
+ let result = case x {
+ [] -> "Empty list"
+ [1] -> "List of just 1"
+ [4, ..] -> "List starting with 4"
+ [_, _] -> "List of 2 elements"
+ _ -> "Some other list"
+ }
+ io.debug(result)
+}
diff --git a/lessons/src/lesson025_list_patterns/text.html b/lessons/src/lesson025_list_patterns/text.html
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+<p>
+ Lists and the values they contain can be pattern matched on in case
+ expressions.
+</p>
+<p>
+ List patterns match on specific lengths of lists. The pattern <code>[]</code>
+ matches an empty list, and the pattern <code>[_]</code> matches a list with
+ one element. They will not match on lists with other lengths.
+</p>
+<p>
+ The spread pattern <code>..</code> can be used to match the rest of the list.
+ The pattern <code>[1, ..]</code> matches any list that starts with
+ <code>1</code>. The pattern <code>[_, _, ..]</code> matches any list that has
+ at least two elements.
+</p>