Difference between revisions of "FP Laboratory 1/cs"
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Using the installation guide from [[Functional programming | Functional programming]] prepare your working environment. | Using the installation guide from [[Functional programming | Functional programming]] prepare your working environment. |
Revision as of 07:57, 6 September 2019
Contents
Pracovní prostředí
Using the installation guide from Functional programming prepare your working environment.
How to verify it is working?
- Run
ghci
from 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.hs
and 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 b
that computesc
based on . Necessary functions can be found: Hoogle - Open
ghci
and run the implemented function with3 4
. File can be loaded using command:l
(:load
) and reloaded with:r
(:reload
).
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.hs
with 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.