GHC does type type-defaulting as well, at least whenever you export a module it will monomorphize any ambiguous numeric types to the types in default
types for the module, which is by defaulted to:
default (Integer, Double)
See the section "4.3.4 Ambiguous Types, and Defaults for Overloaded Numeric Operations" in the Haskell specification.
You can disable this with the pragma {-# LANGUAGE NoMonomorphismRestriction #-}
in the module you want to export with toplevel numeric polymorphic types left intact.