ABSTRACT. We introduce the functional language IQu which, under the paradigm “quantum data & classical control” and in accordance with the model QRAM, allows to define and manipulate quantum circuits and quantum states on which we can execute partial measurement. IQu tailors a lot of ideas from the design of Idealized Algol (roughly, PCF extended with local stores and assignment) and its side-effect management. These ideas play a crucial role in the language design: each quantum co-processor is formalized by means of a quantum register (storing a quantum state) that can be modified by quantum directives (lists of unitary gates). The linearity of quantum states is assured by a one-to one correspondence between quantum states and quantum registers. We adapt the type system of Idealized Algol for typing both quantum-registers and quantum-directives. The types for quantum registers are parametric on the number of qubits and their linearity is granted for free. IQu operates on quantum circuits as they were classical data so no restriction exists on their duplication.