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authorLouis Pilfold <louis@lpil.uk>2024-01-23 14:41:22 +0000
committerLouis Pilfold <louis@lpil.uk>2024-01-23 14:41:22 +0000
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treeedff3551c32e060645e29be4304ca496c35e3128 /src/content/chapter0_basics/lesson14_blocks
parent2e5b4cb878569e56811f4f58facbe7aa60ab7327 (diff)
downloadtour-1aa782ae22aa55d44ba4ed01ad447915dc7802cb.tar.gz
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Add equality lesson
Diffstat (limited to 'src/content/chapter0_basics/lesson14_blocks')
-rw-r--r--src/content/chapter0_basics/lesson14_blocks/code.gleam13
-rw-r--r--src/content/chapter0_basics/lesson14_blocks/text.html23
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diff --git a/src/content/chapter0_basics/lesson14_blocks/code.gleam b/src/content/chapter0_basics/lesson14_blocks/code.gleam
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+import gleam/io
+
+pub fn main() {
+ let fahrenheit = {
+ let degrees = 64
+ degrees
+ }
+ // io.debug(degrees) // <- This will not compile
+
+ // Changing order of evaluation
+ let celsius = { fahrenheit - 32 } * 5 / 9
+ io.debug(celsius)
+}
diff --git a/src/content/chapter0_basics/lesson14_blocks/text.html b/src/content/chapter0_basics/lesson14_blocks/text.html
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+<p>
+ Blocks are one or more expressions grouped together with curly braces. Each
+ expression is evaluated in order and the value of the last expression is
+ returned.
+</p>
+<p>
+ Any variables assigned within the block can only be used within the block.
+</p>
+<p>
+ Try uncommenting <code>io.debug(degrees)</code> to see the compile error from
+ trying to use a variable that is not in scope.
+</p>
+<p>
+ Blocks can also be used to change the order of evaluation of binary operators
+ expressions.
+</p>
+<p>
+ <code>*</code> binds more tightly than <code>+</code> so the expression
+ <code>1 + 2 * 3</code> evaluates to 7. If the <code>1 + 2</code> should be
+ evaluated first to make the expression evaluate to 9 then the expression can be
+ wrapped in a block: <code>{ 1 + 2 } * 3</code>. This is similar to grouping
+ with parentheses in some other languages.
+</p>