2.3 KiB
2.3 KiB
| type |
|---|
| mixed |
Function definitions
- We don't have a return, we have an expression
- Calling a function is done like this:
name arg1 arg2 ... argn
Or in this case:
add 1 2 -- This will return 3
Types
name :: <type>
Integer
x :: Integer
x = 1
Boolean
y :: Bool
y = True
Float
z :: Float
z = 1.6
-
Data Types
- Int: platform-dependent precision integers
- Char: character literals, functions from Data.Char module (e.g., isSpace, isDigit, isAlpha, isLower, isUpper, toLower, toUpper, digitToInt)
- Tuple types: (e1, ..., en), functions fst and snd for pairs
-
Type classes
Num: numeric types (e.g., Int, Integer, Float, Double)Eq: equality types, with operators==and/=Ord: ordered types, with operators<and<=
Infix functions
- Functions written between their arguments, rather than before them.
5 + 3is an infix function- By default, functions with symbols (like
+,-,*) are infix. - You can also make any function infix by surrounding it with backticks (
`).
Continuing with the add example, we could call it like this:
add 5 3 -- 8
but we could also do this
5 `add` 3
This achieves more natural placement of the function (in some cases).
Types in functions
We define them as a chain of types for the arguments (including the return type) with ->
In the add example:
add :: Integer -> Integer -> Integer
add x y = x + y
Let
- Save the result of an expression and then return it
- Defines variables before the main expression
let <name> = <expression> in <result>
i.e.
let x = 5
y = 10
in x + y -- This will "return" x+y = 15
Where
- Inverse of let - defines variables after the main expression
- Makes more intuitive mathematical sense
<result> where <name> = <expression>
i.e.
x + y where
x = 5
y = 10
If branches
If then else (ternary)
equalize x y =
if xLarger then x - 1 else y - 1
where
xLarger = x > y