L18 : Design of NPROMA routines
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NPROMA routines should be individual subroutines, allowing for :

- automatic interface generation
- separate compilation
- easiness of automatic analysis and transformation

In particular implementing a routine or a set of subroutines inside a module in
order to benefit from the automatic generation of an interface in a .mod file
should be prohibited.

The use of modules should be restricted to derived types definition and implementation (methods).