Notationally, parantheses seem to be very popular. Almost too popular. The following is a collection of all the different notations that I've found paranthesis used for. If you would like to add one, send me a pull request on Github.

Name | Usage | Locations (non-exhaustive) |
---|---|---|

Function application | The value $f(2)$ is, oddly, ... | Mathematics, programming |

Precedence | $2+(3\cdot5) \neq (2 + 3) \cdot 5$ | Mathematics, programming |

Parentheticals | The man (who wore flannel) began ... | Writing |

Ideal | $(N) := \{kN \mid k \in \mathbb Z\}$ | Ring Theory |

Tuples | $(x,y)=(0.5, 1.7)$ | Mathematics, programming |

Indexing | `item = my_list(i)` | MATLAB |

$n$-dimensional sequences | Consider the sequence $(a_{ij})$ ... | Mathematics |

Multiplication | $(5)(17) = 85$ | Mathematics |

S-Expression | `(f x y z)` | Lisps |

Interval notation | ...so for any $x$ in $[0, +\infty)$ we have ... | Mathematics |

$n$ choose $k$ | ${n \choose k} = \frac{n!}{k!(n-k)!}$ | Mathematics |

Matrices | $I_2 := \left( \begin{matrix} 1 & 0 \\ 0 & 1 \end{matrix} \right)$ | Mathematics |

Greatest common divisor | $(a, b) := \mathit{gcd}(a, b)$ | Mathematics |

Generator expression | `(f(x) for x in li)` | Python |

Function shorthand | `(+)` , `(+2)` , `(3*)` | Haskell |

Congruence | $5 \equiv 15\ (\text{mod } 10)$ | Mathematics |

Labels | See example (B) or refer back to (II) to... | Writing |

Unit | `()` | Haskell |

Enumeration | Two things: 1) ...; and 2) ... | Writing |

Emoticon | :) :( ;) :'( | Texting |

Permutation Cycles | $(1 3)(2)(4 6 5)$ | Mathematics |