Moving to Functional

[Gribouillis]

Here is my attempt in a non imperative style

import itertools as itt
import numpy as np
    
def count_incr(rec):
    return np.array(RecRan(rec, j) for j in range(10))
 
def ireport_group(date, irec):
    return itt.chain(
        (StrRec(rec) for rec in irec),
        (Summary(len(irec),
            list(np.sum(count_incr(rec) for rec in irec)), Strdate(date)),))

def Report():
    return ''.join(
        itt.chain.from_iterable(
            ireport_group(date, list(irec))
                for date, irec in itt.groupby(Load(), key=RecToDate)))