Coding just likes Art
This is the blog about the coding, the whole coding and nothing but the coding , so God would help me become a better developer.
Learning Haskell (WIP)
1 Environment Install
1.1 Dependencies
Glasgow Haskell Compiler (GHC) - The compiler for Haskell. Cabal - Package description format. Stack - Package management tool.
1.2 Get Start
brew update # upgrade HomeBrew brew install haskell-stack # install package management tool Stack stack new # download Haskell runtime environment
1.3 Emacs Haskell-mode
M-x package-refresh-contents M-x package-install RET haskell-mode
(setq haskell-program-name "GHCI_PATH")
1.4 Haskell Test
putStrLn "Hello World" 92 `div` 13
2 Haskell Features
- Referential Transparency
- Type Inference
- Lazy
- Statically Typed
3 Basic Rules
3.1 Define and Evaluate Function
let f x = 1 + x -- Same as define ~f~ in a file and load it using :l f 2 -- 3
3.2 If Expression
let double'Small'Num x = (if x > 100 then x else 2 * x) + 1 double'Small'Num 101 -- 102
3.3 List
1 : [2,3] ++ [4,5] ++ [] -- [1,2,3,4,5]
('H' : "ello" ++ " " ++ "World") !! 1 -- 'e'
[3,2,1] <= [3,2,2] -- True
let l = [1,2,3,4]
(tail l) ++ [head l] -- [4,1,2,3]
(last l) : (init l) -- [4,1,2,3]
length l -- 4
null [] -- True
reverse l -- [4,3,2,1]
take 2 l -- [1,2]
drop 2 l -- [3,4]
maximum l -- 4
sum l -- 10
product l -- 24
5 `elem` l -- False
3.4 Range
[1..4] -- [1,2,3,4] ['a'..'d'] -- "abcd" [1,3..7] -- [1,3,5,7] [13,26..4*13] -- [13,26,39,52]
3.5 List Comprehension
[ x*2 | x<-[1..3], x/=2 ] -- [2,6] let xxs = [[1..3], [2..4], [3..5]] [[x | x <- xs, even x] | xs <- xxs] -- [[2], [2,4], [4]] [x+y | x <- [1..3], y <- [2..5]] -- [3,4,5,6,4,5,6,7,5,6,7,8]
