Difference between revisions of "FP Laboratory 1"
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| − | == | + | == Working environment == <!--T:1--> |
| − | <syntaxhighlight lang="Haskell" | + | <!--T:2--> |
| − | + | Using the installation guide from [[Functional programming | Functional programming]] prepare your working environment. | |
| − | + | ||
| − | + | ===How to verify it is working?=== <!--T:3--> | |
| − | + | ||
| − | ghci> | + | <!--T:4--> |
| − | + | *Run <code>ghci</code> from the command line. it will start GHC Interpreter, the output should be something like this: | |
| − | + | </translate> | |
| − | + | <syntaxhighlight lang="Haskell" class="myDark" > | |
| − | + | GHCi, version 8.6.5: http://www.haskell.org/ghc/ :? for help | |
| + | Prelude> | ||
| + | </syntaxhighlight > | ||
| + | <translate> | ||
| + | <!--T:5--> | ||
| + | *If you write expression, for example <code>1+2*3</code>, it should be evaluated. You can close this interpreter by typing <code>:q</code>. | ||
| + | *Open Visual Studio Code, create a file <code>simple.hs</code> and put there following lines of code: | ||
| + | </translate> | ||
| + | <syntaxhighlight lang="Haskell" > | ||
| + | doubleMe x = x * x | ||
| + | |||
| + | plus x y = x + y + 'a' | ||
| + | </syntaxhighlight > | ||
| + | <translate> | ||
| + | <!--T:6--> | ||
| + | It should report a problem in function <code>plus</code> (you can not use <code>+</code> with letter, it can be repaired by removing <code>+ 'a'</code>). Report from VS Code is refreshed whenever the source file is saved on disk. | ||
| + | |||
| + | == First program in Haskell == <!--T:7--> | ||
| + | In your favorite development environment (VS Code by default): | ||
| + | * Crate a file <code>simple.hs</code>. | ||
| + | * Create a function <code>pythagoras a b</code> that computes <code>c</code> based on <math>c^2 = a^2 + b^2 \,,</math>. Necessary functions can be found: [https://hoogle.haskell.org/ Hoogle] | ||
| + | * Open <code>ghci</code> and run the implemented function with <code>3 4</code>. File can be loaded using command <code>:l</code> (<code>:load</code>) and reloaded with <code>:r</code> (<code>:reload</code>). | ||
| + | </translate> | ||
| + | <div class="mw-collapsible mw-collapsed" data-collapsetext="Hide solution" data-expandtext="Show solution"> | ||
| + | <syntaxhighlight lang="Haskell"> | ||
| + | pythagoras a b = sqrt (a*a + b*b) | ||
| + | </syntaxhighlight> | ||
| + | [[File:Tryit.png|center|60px|Try it!|link=https://rextester.com/DEAQ69276]] | ||
| + | </div> | ||
| + | <div style="clear:both"></div> | ||
| + | <translate> | ||
| + | == Real first program in Haskell == <!--T:8--> | ||
| + | |||
| + | <!--T:9--> | ||
| + | If you are complaining, that all programming courses should start with printing <code>"Hello world!"</code> on the screen and that is why previous task sucks. Do the following exercise. | ||
| + | *Crate a file <code>firstProgram.hs</code> with following content: | ||
| + | </translate> | ||
| + | <syntaxhighlight lang="Haskell"> | ||
| + | main = do putStr "Hello world!" | ||
</syntaxhighlight > | </syntaxhighlight > | ||
| + | <translate> | ||
| + | <!--T:10--> | ||
| + | *Compile it with 'GHC compiler' (command <code>ghc</code>). | ||
| + | *It should produce an executable file <code>firstProgram(.exe)</code>, run this file. | ||
</translate> | </translate> | ||
Latest revision as of 14:59, 20 September 2021
Contents
Working environment
Using the installation guide from Functional programming prepare your working environment.
How to verify it is working?
- Run
ghcifrom the command line. it will start GHC Interpreter, the output should be something like this:
GHCi, version 8.6.5: http://www.haskell.org/ghc/ :? for help
Prelude>
- If you write expression, for example
1+2*3, it should be evaluated. You can close this interpreter by typing:q. - Open Visual Studio Code, create a file
simple.hsand put there following lines of code:
doubleMe x = x * x
plus x y = x + y + 'a'
It should report a problem in function plus (you can not use + with letter, it can be repaired by removing + 'a'). Report from VS Code is refreshed whenever the source file is saved on disk.
First program in Haskell
In your favorite development environment (VS Code by default):
- Crate a file
simple.hs. - Create a function
pythagoras a bthat computescbased on . Necessary functions can be found: Hoogle - Open
ghciand run the implemented function with3 4. File can be loaded using command:l(:load) and reloaded with:r(:reload).
pythagoras a b = sqrt (a*a + b*b)
Real first program in Haskell
If you are complaining, that all programming courses should start with printing "Hello world!" on the screen and that is why previous task sucks. Do the following exercise.
- Crate a file
firstProgram.hswith following content:
main = do putStr "Hello world!"
- Compile it with 'GHC compiler' (command
ghc). - It should produce an executable file
firstProgram(.exe), run this file.
