# bubble-operator-upwards

An utility function in Quicklisp.

Project author | Jean-Philippe Paradis | |
---|---|---|

Project type | Library | |

Programming language | Common Lisp | |

Status | Ready-to-use | |

License | Public Domain | |

Library type | Utility function | |

Project complexity | Trivial | |

Latest release | Version | 1.0 |

Date | 4 nov 2012 | |

Quicklisp
(Nov 2012 dist and later) |
Status | Available |

Version | Latest |

# External library pages

⬉ | Depends on | Depended on by |
---|---|---|

Directly | Nothing | Nothing |

Indirectly | Nothing | Nothing |

`bubble-operator-upwards`

is a function that "bubbles an operator upwards" in a form, demultiplexing all alternative branches by way of cartesian product. This operation is notably useful for easy implementation of certain kinds of shorthand notations in macros. A `cartesian-product`

function is also exported, as it's needed to implement the main function.

# ⚓

`(``bubble-operator-upwards`

'and '(plate (and ham eggs) beans))
=>
(AND (PLATE HAM BEANS)
(PLATE EGGS BEANS))

`(``bubble-operator-upwards`

'alt '(section (alt 1 2 3) - (alt "a" "b"))
:result-kind :branches)
=>
((SECTION 1 - "a") (SECTION 1 - "b")
(SECTION 2 - "a") (SECTION 2 - "b")
(SECTION 3 - "a") (SECTION 3 - "b"))

`(``bubble-operator-upwards`

'or '(>> (or ul ol)
(or (:class (or "important" "urgent"))
(id "first-priority"))))
=>
(OR (>> UL (:CLASS "important"))
(>> UL (:CLASS "urgent"))
(>> UL (ID "first-priority"))
(>> OL (:CLASS "important"))
(>> OL (:CLASS "urgent"))
(>> OL (ID "first-priority")))

# ⚓

First of all, in the way of packages there's the `bubble-operator-upwards`

package, which is also nicknamed `bubble-op-up.`

It exports the functions `bubble-operator-upwards`

and `cartesian-product`

. Explicitly `(:import-from)`

only those you need or explicitly package-qualify the symbols. Don't `(:use)`

!

Function

`bubble-operator-upwards`

`operator``form`&key (`result-kind``:abridged`

) (`if-collapsed``nil`

) (`collapsed-identity`(ecase`result-kind`((:full`:abridged`

) (list`operator`)) (:branches`nil`

))) =>`result`-
Bubbles

`operator`upwards in`form`, demultiplexing all alternative branches by way of cartesian product. Hard to describe formally, but the examples above should give some inspiration for the basic effect, and some experimentation in the REPL is recommended.`result-kind`is one of`:branches`

,`:full`

or`:abridged`

`:branches`

simply returns the demultiplexed branches.`:full`

returns the same`result`as`:branches`

would, except wrapped in a cons whose CAR is`operator`.`:abridged`

returns the same result as`:full`

would, except if there's only one branch, only that branch is returned, without the wrapping.

`if-collapsed`and`collapsed-identity`determine what to do if the number of branches "collapses" to zero.`if-collapsed`is`:error`

or`nil`

. If it's`nil`

and the result is indeed collapsed, then the value of`collapsed-identity`will be returned. Function

`cartesian-product`

&rest`possibility-groups`=>`cartesian-product`-
Returns the cartesian-product of all possible combinations from

`possibility-groups`, as a list. This function is inherently needed to implement`bubble-operator-upwards`

, so might as well export it...`(`

`cartesian-product`

'(1 2) '(a b c)) => ((1 A) (1 B) (1 C) (2 A) (2 B) (2 C))