Nathan Sanders has posted a Fing implementation here:

[link:github.com]

Fing is F# API Search. It's based on the idea of Hoogle, although it is
not a port. Fing has two uses. The obvious is to search for a function by name:

> Fing.nameFind "abs";;

But Fing is not really needed for this; Bing (or Google) will just do as well
with "site:msdn.com abs". Although, it is nice for symbols:

> Fing.nameFind "( ~~~ )";;

Where Fing is really useful is when you are about to write something
that is very likely to already exist in the standard library. Say you
want a function that looks for an item in a list that satisfies some
property and returns None if it can't find one. The type of this function is

('a -> bool) -> list<'a> -> 'a option
(the property) (the list) (the optional return value)

So you say

> Fing.textFind "('a -> bool) -> list<'a> -> 'a option";;

('a -> bool) -> list<'a> -> 'a option
Results:
List.tryFind (('a -> bool) -> list<'a> -> option<'a>)