urbit/pub/docs/dev/hoon/runes/bc/bcbr.md

bucbar `$|` %bcbr
=================

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Atom or cell
------------

`$|` is a tile rune that produces a [`%reed`](), a tile whose [icon]()
is a [fork]() between two nouns: an [atom]() of `tile` `p` and a cell of
`tile` `q`. `$|` is similar to [`$?`](), but is more strict in that in
only contains one atom tile and one cell tile.

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### Produces

[`Tile`](): `[%reed p=tile q=tile]`

### Sample

`p` is a [`tile`]() `q` is a [`tile`]()

### Tall form

    $|  p
        q

### Wide form

    $|(p q)

### Irregular form

None

### Examples

    ~zod/try=> *$|(~ [~ u=@])
    ~
    ~zod/try=> :type; *$|(~ [~ u=@])
    ~
    u(@)

    ++  list  |*  a=_,*                                     ::  null-terminated list
              $|(~ [i=a t=(list a)])                        ::

In `++list`, `$|` specifies that every element in a noun that can be
cast to a `++list` is either the atom `~` or the cell
`[i=a t=(list a)]`.