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authorLouis Pilfold <louis@lpil.uk>2023-12-21 14:03:41 +0000
committerLouis Pilfold <louis@lpil.uk>2023-12-21 14:03:41 +0000
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-rw-r--r--src/content/chapter1_functions/lesson05_pipelines/code.gleam19
-rw-r--r--src/content/chapter1_functions/lesson05_pipelines/text.html25
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diff --git a/src/content/chapter1_functions/lesson05_pipelines/code.gleam b/src/content/chapter1_functions/lesson05_pipelines/code.gleam
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+import gleam/io
+import gleam/string
+
+pub fn main() {
+ // Without the pipe operator
+ io.debug(string.drop_left(string.drop_right("Hello, Joe!", 1), 7))
+
+ // With the pipe operator
+ "Hello, Mike!"
+ |> string.drop_right(1)
+ |> string.drop_left(7)
+ |> io.debug
+
+ // Changing order with function capturing
+ "1"
+ |> string.append("2")
+ |> string.append("3", _)
+ |> io.debug
+}
diff --git a/src/content/chapter1_functions/lesson05_pipelines/text.html b/src/content/chapter1_functions/lesson05_pipelines/text.html
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+<p>
+ It's common to want to call a series of functions, passing the result of one
+ to the next. With the regular function call syntax this can be a little
+ difficult to read as you have to read the code from the inside out.
+</p>
+<p>
+ Gleam's pipe operator <code>|></code> helps with this problem by allowing you
+ to write code top-to-bottom.
+</p>
+<p>
+ The pipe operator takes the result of the expression on its left and passes it
+ as an argument to the function on its right.
+</p>
+<p>
+ It will first check to see if the left-hand value could be used as the first
+ argument to the call. For example, <code>a |> b(1, 2)</code> would become
+ <code>b(a, 1, 2)</code>. If not, it falls back to calling the result of the
+ right-hand side as a function, e.g., <code>b(1, 2)(a)</code>
+</p>
+<p>
+ Gleam code is typically written with the "subject" of the function as the
+ first argument, to make it easier to pipe. If you wish to pipe to a different
+ position then a function capture can be used to insert the argument to the
+ desired position.
+</p>