We present a probabilistic version of PCF, a well-known simply typed
universal functional language. The type hierarchy is based on a single ground
type of natural numbers. Even if the language is globally call-by-name, we
allow a call-by-value evaluation for ground type arguments in order to provide
the language with a suitable algorithmic expressiveness. We describe a
denotational semantics based on probabilistic coherence spaces, a model of
classical Linear Logic developed in previous works. We prove an adequacy and an
equational full abstraction theorem showing that equality in the model
coincides with a natural notion of observational equivalence
