357 lines
14 KiB
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357 lines
14 KiB
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<a href="/20241210233721-brain_moc.html"> <img src="/assets/gr.png" alt="Site Logo" class="banner-logo" /> </a>
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<div id="updated">Updated: 2025-12-28 Sun 19:48</div>
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<article class="stack-pane pane-root" data-url="/20241212013207-haskell_notes.html">
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</div>
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<h1 class="title">haskell<sub>notes</sub></h1>
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<div class="title-metadata">
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<span class="metadata-item">
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<span class="metadata-label">planted:</span>
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<span class="metadata-value">2024-12-12</span>
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</span>
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<span class="metadata-item">
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<span class="metadata-label">last tended to:</span>
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<span class="metadata-value">2025-12-28</span>
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</div>
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</div>
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<div id="outline-container-org156babe" class="outline-2">
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<h2 id="org156babe"><a href="#org156babe">Haskell Notes</a></h2>
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<div class="outline-text-2" id="text-org156babe">
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</div>
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<div id="outline-container-org34b124b" class="outline-3">
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<h3 id="org34b124b"><a href="#org34b124b">Introduction</a></h3>
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<div class="outline-text-3" id="text-org34b124b">
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<p>
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Haskell is a purely functional programming language with strong static typing and <a href="20241212013902-lazy_evaluation.html#ID-63456626-b34e-46d9-b85e-0f1f5724aa83">lazy<sub>evaluation</sub></a> . It was named after the logician Haskell Curry. It is widely used in academia and industry for teaching and research as well as for writing industrial applications.
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</p>
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</div>
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</div>
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<div id="outline-container-org4320f82" class="outline-3">
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<h3 id="org4320f82"><a href="#org4320f82">Features of Haskell</a></h3>
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<div class="outline-text-3" id="text-org4320f82">
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<ul class="org-ul">
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<li>Purely Functional: Functions in Haskell are pure, meaning they don’t have side effects.</li>
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<li>Strong Static Typing: Types are checked at compile time, reducing runtime errors.</li>
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<li>Lazy Evaluation: Expressions are not evaluated until their values are needed.</li>
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<li>Type Inference: Haskell can automatically infer types, making the code more concise.</li>
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<li>Concise Syntax: Haskell’s syntax is clean and concise, making it easy to read and write.</li>
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</ul>
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||
</div>
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||
</div>
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||
<div id="outline-container-org4cb27d6" class="outline-3">
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<h3 id="org4cb27d6"><a href="#org4cb27d6">Getting Started with Haskell</a></h3>
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<div class="outline-text-3" id="text-org4cb27d6">
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<ul class="org-ul">
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<li>Installation: To get started with Haskell, you need to install the Glasgow Haskell Compiler (GHC). You can download it from <a href="https://www.haskell.org/downloads/">Download</a></li>
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<li>Basic Syntax:
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<ul class="org-ul">
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<li>Comments: Single line comments start with `–`, and multi-line comments are enclosed within `{-` and `-}`.</li>
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<li>Modules: Code is organized into modules, which can be imported using the `import` keyword.</li>
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</ul></li>
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</ul>
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</div>
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</div>
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||
<div id="outline-container-org630e53b" class="outline-3">
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<h3 id="org630e53b"><a href="#org630e53b">Basic Concepts</a></h3>
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<div class="outline-text-3" id="text-org630e53b">
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<ul class="org-ul">
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<li><p>
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Functions: Functions are first-class citizens in Haskell. A function definition looks like this:
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</p>
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<div class="org-src-container">
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<pre class="src src-haskell">add :: Int -> Int -> Int
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add x y = x + y
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</pre>
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</div>
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<p>
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This defines a function <b>add</b> that takes two integers and returns their sum.
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</p></li>
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<li>Types and Type Classes: Types are a crucial part of Haskell. You define types using the `data` keyword, and type classes using the `class` keyword.</li>
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</ul>
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||
</div>
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||
</div>
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||
<div id="outline-container-orge2b895f" class="outline-3">
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||
<h3 id="orge2b895f"><a href="#orge2b895f">Example</a></h3>
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||
<div class="outline-text-3" id="text-orge2b895f">
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||
<p>
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||
Here’s a simple example to demonstrate some basic features of Haskell:
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||
</p>
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||
<div class="org-src-container">
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||
<pre class="src src-haskell">-- Define a new data type
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data Shape = Circle Float | Rectangle Float Float
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-- Define a function to calculate the area of a shape
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area :: Shape -> Float
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area (Circle r) = pi * r^2
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area (Rectangle l w) = l * w
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-- Example usage
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main = do
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let c = Circle 10
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let r = Rectangle 5 7
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print (area c)
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print (area r)
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</pre>
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||
</div>
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||
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||
<p>
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||
This example defines a new data type Shape with two constructors, Circle and Rectangle, and a function area that calculates the area of a shape.
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||
</p>
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||
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||
<p class="backlinks-section" id="backlinks">
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||
Backlinks
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||
</p>
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<ul class="org-ul backlinks-list">
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<li><a href="20241210001045-technical.html#ID-2f285f04-fcf4-4ade-a1ac-2c50b43d529a">Technical MOC</a></li>
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</ul>
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</div></article></div></div>
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Copyright © 2022-2025 Zaine Qayyum. All rights reserved unless otherwise noted.</div></div>
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