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6.7 Operators

`nip2`'s expression syntax is almost exactly the same as C, with a few small changes. Table 6.2 lists all of `nip2`'s operators in order of increasing precedence. If you've used C, the differences are:

- C's `?:` operator becomes `if-then-else`, see above

- Like almost every functional language, `nip2` uses square brackets for list constants (see §6.7.5), so to index a list, `nip2` uses `?`

- The `:` operator is infix list cons, see §6.8

- `nip2` adds `@` for function composition, see §6.7.6

- The `++` operator becomes an infix concatenation operator, again see §6.8

- `nip2` adds `**` for raise to power

The only slightly tricky point is that function application binds very tightly (only list index and class project bind more tightly). So the expression:

> | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
> | `jim = fred 2 + 3` |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

binds as:

> | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` | `` |  | `` |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
> | `jim = (fred 2) + 3` |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

This is almost always the behaviour you want.

There are two special equality tests: `===` and `!==`. These test for pointer equality, that is, they return `true` if their arguments refer to the same object. These are occasionally useful for writing interactive functions.

Table 6.2: `nip2` operators in order of increasing precedence
Operator | Associativity | Description
`if then else` | Right | If-then-else construct
`,` | Left | List/complex separator
`||` | Left | Logical or
`&&` | Left | Logical and
`@` |  | Function composition (see §6.7.6)
`|` | Left | Bitwise or
^ | Left | Bitwise exclusive or
`&` | Left | Bitwise and
`==` | Left | Equal to
`!=` |  | Not equal to
`===` |  | Pointer equal to
`!==` |  | Pointer not equal to
`<` | Left | Less than
`<=` |  | Less than or equal to
`>` |  | Greater than
`>=` |  | Greater than or equal to
`«` | Left | Left shift
`»` |  | Right shift
`+` | Left | Addition
`-` |  | Subtraction
`*` | Left | Multiplication
|  | Division
`%` |  | Remainder after division
`!` | Left | Logical negation
`~` |  | One's complement
`++` |  | Join (see §6.8)
`-` |  | Unary minus
`+` |  | Unary plus
`(`type`)` |  | Type cast expression
`**` | Right | Raise to power
`:` |  | List CONS (see §6.8)
space | Left | Function application
`?` | Left | List index (see §6.8)
`.` | Left | Class project (see §6.11)

Subsections

- 6.7.1 The real type
- 6.7.2 The complex type
- 6.7.3 The character type
- 6.7.4 The boolean type
- 6.7.5 The list type
- 6.7.6 The function type
- 6.7.7 The image type

Next: 6.7.1 The real type Up: 6. Programming Previous: 6.6 Evaluation Contents