Philippe Meunier wrote:
Jon Rafkind wrote:
Attached is a patch that changes the prefixes that mzlib/trace prints
depending on whether a function call is occuring or if a result is being
returned. "<" is a function call and ">" is a return value.
That looks backward to me: the trace library represents the stack of
function calls horizontally from left to right, so for a function call
I would expect it to use ">" to point in the direction in which the
stack grows... I don't see anything wrong with using "|" anyway (if
it's used the right way, see below).
Eli pointed the same out to me so I'll change it to >.
I find this is easier to read than the current ambiguous "|".
I agree that the current output:
|(fact 5)
| (fact 4)
| |(fact 3)
| | (fact 2)
| | |(fact 1)
| | | (fact 0)
| | | 1
| | |1
| | 2
| |6
| 24
|120
120
could be better. I understand why 120 appears twice but I find it a
bit confusing, and I also think it would be better to use "|" to
symbolize actual stack frames rather than just use it along with " "
for vertical alignment purposes, even if that means using twice the
amount of horizontal space to represent the stack. Something like
this:
The output already shows you the number of stack frames. The number of
stack frames is basically the amount of space before the input/output.
Only one | is printed for every two stack frames, I guess to make the
output look nicer.
(fact 5)
| (fact 4)
| | (fact 3)
| | | (fact 2)
| | | | (fact 1)
| | | | | (fact 0)
| | | | | 1
| | | | 1
| | | 2
| | 6
| 24
120
or like this, if you imagine that (fact 2) is somehow a tail call:
(fact 5)
| (fact 4)
| | (fact 3)
| | (fact 2)
| | | (fact 1)
| | | | (fact 0)
| | | | 1
| | | 1
| | 6
| 24
120
I think you mean (fact 3) is a tail call, but yes the trace output does
that too (condense tail calls so they take up the same amount of output).
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