Revert "Use recursion to fix inference failure with tuples (#78)"

This reverts commit e1ef21b.

src/base.jl

@@ -1,13 +1,6 @@
 # predefined adaptors for working with types from the Julia standard library
 
-# Use recursion to avoid inference bail-out in `map`
-#adapt_structure(to, xs::Union{Tuple,NamedTuple}) = map(adapt(to), xs)
-adapt_structure(to, xs::NamedTuple) = map(adapt(to), xs)
-adapt_structure(to, xs::Tuple) = _adapt_tuple_structure(to, xs)
-_adapt_tuple_structure(to, xs::Tuple) =
-  (adapt(to, first(xs)), _adapt_tuple_structure(to, Base.tail(xs))...)
-_adapt_tuple_structure(to, xs::Tuple{}) = ()
-_adapt_tuple_structure(to, xs::Tuple{<:Any}) = (adapt(to, first(xs)), )
+adapt_structure(to, xs::Union{Tuple,NamedTuple}) = map(adapt(to), xs)
 
 
 ## Closures