Using haskell platform please

Write a function: grade :: StudentMark -> Char which returns a student's grade from a percentage mark. Marks of 70 or above get an A grade, marks between 60 and 69 get a B, between 50 and 59 a C, between 40 and 49 a D, and marks below 40 get an F. Write a function: capMark :: StudentMark -> Student Mark which caps the mark of a student to a maximum of 40. Write a function: grade :: StudentMark -> Char which returns a student's grade from a percentage mark. Marks of 70 or above get an A grade, marks between 60 and 69 get a B, between 50 and 59 a C, between 40 and 49 a D, and marks below 40 get an F. Write a function: capMark :: StudentMark -> Student Mark which caps the mark of a student to a maximum of 40