# `~` — NOT / Without

Function. Ranks: `0` monadic, `∞ ∞` dyadic

`~Y` negates Booleans, pervasively.

``` bpl
~0 1               ⍝ $t $f
```

`X~Y` removes the major cells of `X` found among the major cells of `Y`,
retaining order and repetitions. Uses tolerant matching.

``` bpl
1 2 1 3~2 4        ⍝ 1 1 3
"banana"~"an"       ⍝ "b"
[1 2⋄3 4⋄1 2]~[1 2⋄] ⍝ [3 4⋄]
```

`Y` must have rank 1 or more. So to remove one character, write it as a
string. `' '` is a unit. `" "` is a one-item vector.

``` bpl
"a b c"~" "         ⍝ "abc"
```

## Inverse

`~⁻¹Y` is `~Y`.

``` bpl
~⁻¹1 0   ⍝ $f $t
```

## Errors

- `RANK`: `Y` is a unit
- `LENGTH`: the major cells of `X` and `Y` differ in shape