These elementary problems require you to translate algebraic expressions into Haskell.

Algebraic expressions are only useful when values are plugged into them. If we are to make many of them work together we need to be able to talk about how values are plugged into them. The concept of a function can be viewed as a way to do this.

These problems involve composition of functions, that is putting functions together so that the result of one function is passed to another function.

In Haskell, new functions can be built this with with a "dot" operator. For example, f.g can be that function which evaluates f (g x) for any suitable x.

Numbers seldom exist in isolation. Sequences of them are basic to mathematics. Calculus, for example, wouldn't exist without such sequences.

In Haskell sequences of numbers are called lists. You can experiment with them here. Also you can practice writing functions which apply themselves to each element of a sequence. Functions which can apply themselve to achieve repetition are called recursive.

You have seen how Haskell can choose which one of many definitions of a function f to apply. In this section you will look at a general way to choose what to calculate next within one definition.

A major Haskell construct for branching is if...then...else.... The concept is rather simple but the choices that can be made can be rather complex because they depend on something called boolean algebra.

Boolean algebra is an algebra not of numbers but of the values True and False.

These problems ask you to write recursive functions. Recursive functions are functions that appear in their own definition.

This category of problems is conceptually more difficult than the others. We intend to create additional problems to bridge the difficulty gap. Check back every month or so to see what we've added.

Metafunctions (sometimes called higher-level functions) are functions whose parameters or return values are also functions. In these problems you are asked to define or use such functions.