Stability | experimental |
---|---|

Maintainer | byorgey@cis.upenn.edu |

Safe Haskell | None |

An interpretation of species as exponential generating functions, which count labeled structures.

# Documentation

labeled :: EGF -> [Integer]Source

Extract the coefficients of an exponential generating function as
a list of `Integer`

s. Since `EGF`

is an instance of `Species`

, the
idea is that `labeled`

can be applied directly to an expression
of the species DSL. In particular,

is the
number of labeled `labeled`

s `!!`

n`s`

-structures on an underlying set of size `n`

(note that

is guaranteed to be an infinite list).
For example:
`labeled`

s

> take 10 $ labeled octopi [0,1,3,14,90,744,7560,91440,1285200,20603520]

gives the number of labeled octopi on 0, 1, 2, 3, ... 9 labels.