Nested binds

assign4.py

class ValueAndLog:
    def __init__(self, value, log):
        self.value = value
        self.log = log

    def __rshift__(self, func):
        result = func(self.value)
        return ValueAndLog(result.value, self.log + result.log)

    @staticmethod
    def unit(v):
        return ValueAndLog(v, "")

wv3 = (                                                        #wv3 =
    ValueAndLog.unit(4) >> (lambda v0:                         #  v0 <- ValueAndLog.unit(4)
        ValueAndLog(v0*v0, "Squared %d\n" % v0) >> (lambda v1: #  v1 <- ValueAndLog(v0*v0, ...)
            ValueAndLog.unit(2*v1) >> (lambda v2:              #  v2 <- ValueAndLog.unit(2*v1)
                ValueAndLog(1+v2, "Added 1 to %d\n" % v2)      #  ValueAndLog(1+v2, ...)
            )
        )
    )
)

print("Answer:", wv3.value)
print("Log:", wv3.log)