wk 2: functions and lists

purity

function will give the same output for the same input every time with no hidden state changes

pros of purity

• easy to test

• predicatble

• referential transperency

referential transparency meaning

instead of the function call you can just put the result there

immutablility

data structures dont change in functional programming

instead of updating a list you just create a new list

pros of immutability

• no who modifies this variable bugs

• easier debugging bc values dont change randomly

• concurrency is safer: if nothing changes, multiple threads can use the same data safely

recursion

breka problem into smaller parts since we dont need a counter or loop

higher order function

functions are like values that you can pass in other functions like numbers or strings — map, filter, foldr