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Consider the following transcript, resulting from an interaction with a Pico-machine:
A line preceded by a colon is the
actual output from the print
component. We can see how the variable pi
is computed as an approximation to ¹, and then used to initialise a
variable
x.
Assigning the value 0
to a variable zero
fails because zero
hasn't been defined yet; the same operation applied to
x
succeeds. Finally, defining the variable
abc
fails because the expression to the right of the colon references a
non-existent variable xyz.
Note that as each of the valid expressions is entered, a value is
printed out; the effects on the current dictionary are only
noticeable through the availability of new variables as the
evaluation proceeds.