Haskell Float to Int

In Haskell, there are two main ways to convert a floating point number to an integer: using the floor or ceiling functions or using the round function. Here is an overview of these functions:

floor and ceiling

The floor function takes a floating point number and rounds it down to the next integer, while the ceiling function rounds it up to the next integer. For example:

floor 3.7  -- returns 3
ceiling 3.7  -- returns 4
floor (-3.7)  -- returns -4
ceiling (-3.7)  -- returns -3

Note that the functions return an Integral type, which can be converted to an Int type using the fromIntegral function:

let x = floor 3.7 :: Int
let y = ceiling 3.7 :: Int
let z = floor (-3.7) :: Int
let w = ceiling (-3.7) :: Int

round

The round function rounds a floating point number to the nearest integer. If the number is exactly halfway between two integers, it rounds to the even integer. For example:

round 3.2  -- returns 3
round 3.7  -- returns 4
round (-3.2)  -- returns -3
round (-3.7)  -- returns -4

Again, note that the function returns an Integral type, which can be converted to an Int type using the fromIntegral function:

let x = round 3.2 :: Int
let y = round 3.7 :: Int
let z = round (-3.2) :: Int
let w = round (-3.7) :: Int

Conclusion

In Haskell, converting a floating point number to an integer is easy thanks to the floor, ceiling, and round functions. Remember to use the fromIntegral function when you need to convert the result to an Int type.