# Haskell - Expressions

The following illustrates some haskell basics. It can be reproduced using `ghci`.

## Types, Literals, and Constants along with Arithmetic and Boolean Operations

Expression | Type (:t) | Value | Comment 
--- | --- | --- | -------- 
`2` | `Num a => a` | `2` |
`2.03` | `Fractional a => a` | `2.3` |
`'c'` | `Char` | `'c'`
`"hallo"` | `String` | `"hallo"` |
`True` | `Bool` | `True` |
`x=5` | `Num a => a` | `5` | Constant named `x`
`2 + 3` | `Num a => a` | `5` | Similar `-,*,^`
`2 / 3` | `Fractional a => a` | `0.6666666666666666` |
`1 > 2` | `Bool` | `False` | Similar `<, <=, >=, ==, /=`
`True && False` | `Bool` | `False` | Similar `\|\|,not`
`((2+3)*5 > 1) \|\| not (1 > 2)` | `Bool` | `True` | Right part is not evaluated due to lazy evaluation

## Unary Functions

Expression | Type (:t) | Value | Comment 
--- | --- | --- | -------- 
`sqrt(4)` | `Floating a => a` | `2.0` |
`sqrt 4` | `Floating a => a` | `2.0` | Similar `abs,negate,signum,recip`
`sqrt` | `Floating a => a -> a` | |
`sqrt 3^2 + 4^2` | `Floating a => a` | `19.0` |
`sqrt (3^2 + 4^2)` | `Floating a => a` | `5.0` |
`negate(sqrt (3^2 + 4^2))` | `Floating a => a` | `-5.0` |
`negate $ sqrt (3^2 + 4^2)` | `Floating a => a`| `-5.0` | Function **application** operator `$`
`(negate . sqrt) (3^2 + 4^2)`| `Floating a => a`| `-5.0` | Function **composition** operator `.` Reads `negate` **after** `negate . sqrt` | 
`(negate . length) "hallo"` | `Int` | `-5` | 
`negatedRoot = negate . sqrt` | `Floating c => c -> c` | | Constant named `negatedRoot`

## Binary Functions

## Tuples

## Strings

## Control Structures

## Lists