David Mason

I did some reading and got through all the recommended chapters of Learn You A Haskell and Real World Haskell.

Playing around

I also explored several concepts, including composing functions that take multiple arguments. I did not find evidence of any built-in functions, so I ended up defining this:

composeDiadic :: (c -> d) -> (a -> b -> c) -> a -> b -> d
composeDiadic f g x y = f (g x y)

(.:) = composeDiadic

I wanted to make this because I was playing around with lists of lists, and found intersperse, concat, and a function that combines the two: intercalate. I wanted to rewrite intercalate as a little exercise, but it did not like concat . intersperse since (.) does not expect any function that takes 2 arguments.

Lecture 2

Algebraic data types are defined like so:

data MyType = Constructor1
            | Constructor2 Type1
            | Constructor3 TypeA TypeB
  deriving Show

• add deriving Show after a data type definition to automatically make it able to be displayed as a string.
• type constructors and data constructors inhabit different namespaces, so single-constructor types often use the same name for both.

Pattern Matching

• Parens are needed for pattern matching around a data constructor that has one or more parameters.
• Bind the whole value to a name using something like myFuncton name@(Constructor2 a) = <do something with name>