Section 1
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How to repeatedly display a list?
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Last updated
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Date created
Mar 1, 2020
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Section 1
(50 cards)
How to repeatedly display a list?
(cycle [list]) WARNING without a stopping point this is an infinite loop so you could do "take 10 (cycle [1,2,3])"
Prefix Math
div - whole number division (div 8 7) mod - remainder of int division (mod 8 7) abs - absolute value (abs (-7)) negate - change sign of int (negate 7)
How to reverse a list?
reverse [list]
How to make a function doubleUs?
editor filename z y = z x 2 + y x 2
How to make a function doubleSmallNumber using if and then?
doubleSmallNumber x = if x>100 then x else x*2
How to make a the function doubleMe?
editor filename doubleMe x = x+x
How to create a list of lists of numbers named "numbers"? (A lists with lists in them)
numbers :: [[Int]] numbers = [ [ 1,4,7 ] , [ 2,5,8 ] , [ 3,6,9] ],
How to define a list type?
listName :: [Type]
How to find lowest number in a list?
minimum [list]
can you zip two types of lists?
Yes this makes them ordered pairs or tuples
Prefix Boolean
not(bool) (not(true)==false)
Create the same list, two different ways with the values 1,2,3,4
list = [1,2,3,4] list = 1:2:3:4:[ ] (needs to be {values :list}
How to grab a number of elements from the front of a list?
take # [list]
How do you use shell commands while in haskell?
:! [command]
How to find highest number in a list?
maximum [list]
How to create a range that goes by 2, up to 50?
numRangeName :: [Int] numRangeName = [2,4..50]
How to check if a list if empty?
null [list]
How to use init command?
init displays all except last element and the command is init [list]
How to use a function in a function using doubleMe and doubleUs?
editor filename doubleUs x y = doubleMe x + doubleMe y (function have high priority on PEMDAS)
How does comparison work?
compares the first element only unless equal, then it compares the next and if equal compares the next and so on...
Describe basic structure for set builder notation
[expression | values, conditions]
How to get rid of elements from a list?
drop # [list]
How to index in a list?
[list] !! { # } (starts at 0)
How to use the head command?
head displays first element and command is head [list]
How to reload the program?
:reload or :r
What does read do? Also display command
Reads in a string and another value and tries to perform an operation (ex. read "3.4" + 4.0 = 7.4 or read "True" || false = True)
How to make a list of pancake toppings with defined type?
pancakes :: [String] ([[Char]] will work as well) pancakes = ["Chocolate","Banana","Strawberry","Blueberry"]
How to search through commands?
:tab [letter] (the letter can be used to limit search to commands starting with letter)
How to find the product of a list?
product [list]
How to check if an element in a list?
ex. 4 `elem` [3,4,5,6] is true ex. 4 `elem` [3,5,6] is false
Create two functions: Create "Square" that squares input with values 1-10 Create "Cube" that cubes input with values 1-10 and the cubed number is higher than 20
square = [ x*x | x <- [1..10] ] cube = [ x^3 | x <- [1..10], x^3 > 20 ]
How to add two lists together?
list1 ++ list2
Create a function: -outputs "Go!" if Odd -outputs "Pack!" if Even -outputs "Cheeseheads!" otherwise
packers xs = [if x `mod` 2 == 0 && x /=0 then "Go!" else if x `mod` 2 == 1 then "Pack!" else "Cheeseheads!" | x<-xs ]
How to create a list 1-50? and another A-Z?
numRangeName :: [Int] numRangeName = [1..50] ~~~~~~~~~~~~~~~~~~~~~~~~ letRangeName :: [Char] letRangeName = ['A'..'Z']
General Structure of a function call
[function name] [formal parameters] = [result]
Infix Math
+ sum of 2 ints (2 + 3) - difference of 2 ints (2 - 3) x the product of 2 ints (3 * 2) ^ raise a base to a power (2^3)
How to get a length of the list?
length [list]
how to zip two lists?
list1 `zip` list2
How to use tail command?
tail displays all except head and command is tail [list]
How to open up editor?
editor filename extension
How do you use prefix functions as infix?
backticks ( 8 `div` 4)
How to open up Haskell in terminal?
ghci
How to find the sum of a list?
sum [list]
Infix Boolean
&& - and (True && True) || - or (True || False)
How to use last command?
last displays the last element in the list and command is last [list]
Create a function that removes all lowercase letters from a word
removeLower word = [ letter | letter <-word, letter `elem` [ 'A'..'Z']]
How to clear the screen?
:! clear
Single line comment
--
How to load a file into haskell?
:l filename
How to tell what type a value is?
:type <value> or :t
Section 2
(11 cards)