Haskell List related Operations

only elements of the same type can be stored in a list.

　　+ +: Merges two lists into a list. example, [1,2,3]++[4,5,6], the result is [1,2,3,4,5,6].

　　: : Add the preceding element of ":" to the list after ":". The newly added element is in the head position of the list. Example, 1:[2,3,4,5,6], the result is [1,2,3,4,5,6].

　　 !! : Takes the element of the list subscript position. example, [1,2,3,4,5,6]!! 0, the result is 1.

　　Elem: Determines whether an element exists in the list. example, Elem 1 [1,2,3,4,5,6], the result is true. infix form, 1 ' elem ' [1,2,3,4,5,6].

PS: ' is not a single quote in infix form, it is the symbol below the ' ~ ' key on the keyboard.

Second, compare list.

[3] The result of > [2,1] is true.

head: Takes out the first element of the list.

　　tail: Remove all elements except the first element of the list.

　　Last: Takes out the final element of the list.

　　init: Takes out all elements except the last element of the list.

　　Length: Returns the Long value of the list.

　　NULL: Determines whether the list is empty.

　　Reverse: Returns a list's inverse list.

　　Maximum: Takes the maximum value in the list.

　　minimum: Takes the minimum value from the list.

　　sum: Calculates the sum in the list element.

　　Take: Takes the first n elements of a list. example, take 2 [1,2,3,4,5,6], the result is [+].

Drop: Takes the second x element of the list. example, Drop 2 [1,2,3,4,5,6], the result is [3,4,5,6].

Three, range related

[1..10] equivalent to [1,2,3,4,5,6,7,8,9,10]

[' A ' ... ' G '] equivalent to [' A ', ' B ', ' C ', ' d ', ' e ', ' f ', ' G ']

[3,6..10] equivalent to [3,6,9]

　　cycle: Infinite repetition of subsequent content. example, take 3 (cycle []), the result is [1,2,1].

　　repeat: infinite repetition of subsequent elements. example, take 2 (repeat 1), the result is [+].

　　replicate: Repeats the element after N times. example, replicate 2 [[1,2],[1,2]] and the result is [[]].

Iv. representation of a set

　　MoD: Take the remainder operation.

　　Odd: Determine if a number is odd.

[x*2|x<-[1..10]] equivalent [2,4,6,8,10]

[X|x<-[1..10],odd x,mod x 3 = = 0] equivalent to [3,9]

Haskell List related Operations