Haskell Week 9

Syntactic Sugar:

Syntactic sugar is a way of making code more concise which makes it easier to not only write but also easier to read. 

Haskell is notorious for using these little short cuts to make bulky code "sweeter" and easier to understand. For example in a number of examples in this blog the syntax I used was the syntactic sugar equivalent for longer less attractive code.

Here is one example of a map that we looked at earlier in this blog



As you can see I used a map to add one to each of the Integers in the list [1,3,5,7,9] thanks to the magic of syntactic sugar I was able to simply say map (+1) and it knew exactly what I was talking about. The way Haskell can do this is by taking my "sweet" version of syntax and converting it back to the clunky unappealing code. In this case map (+1) translates to \x -> x + 1 which simply makes a lambda and assigns it to the value of x +1.

Another "sweet" piece of syntax in the same example is the list itself. To make the list I simply put the numbers I want to be members and they are added to a new list. Magic right? Wrong! Syntactic sugar! Once again Haskell interpreted my list as (:) 1 ((:) 3 ((:) 5 ((:) 7 ((:) 9 [])) This is the longhand way of creating a list, it uses cons (constructors (NOT LIKE IN JAVA)) to add each element to an empty list until the list is no longer empty.

Other shortcuts (Most of which I have used):

You can let Haskell do a lot of the work for you specifically with sequences. If I were to write print ([1..4]) Haskell would know to return 1,2,3,4 because I set a start point (1) and an end point (4) it then understand the ".." to mean "fill in the blanks here" The longer way to do this would be to use the built in function called enumFromTo and call it on the tuple 1, 5 like so: enumFromTo 1 5.

Even such things as if-else blocks (which really uses cases) are generally written in the short hand. Which I find to be an okay way to do it as long as there is an understanding of the "unsweet" code behind the abbreviations.