144 lines
6.7 KiB
ReStructuredText
144 lines
6.7 KiB
ReStructuredText
*************************************
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Replacing Functions in the Dictionary
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*************************************
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.. code:: ipython2
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from notebook_preamble import D, J, V
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A long trace
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~~~~~~~~~~~~
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.. code:: ipython2
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V('[23 18] average')
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.. parsed-literal::
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. [23 18] average
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[23 18] . average
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[23 18] . [sum 1.0 *] [size] cleave /
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[23 18] [sum 1.0 *] . [size] cleave /
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[23 18] [sum 1.0 *] [size] . cleave /
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[23 18] [sum 1.0 *] [size] . [i] app2 [popd] dip /
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[23 18] [sum 1.0 *] [size] [i] . app2 [popd] dip /
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[23 18] [[sum 1.0 *] [23 18]] [i] . infra first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [sum 1.0 *] . i [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] . sum 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 . 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 1.0 . * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 . [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 [[23 18]] . swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [41.0] . first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 . [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] . [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] [i] . infra first [popd] dip /
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[23 18] [size] . i [41.0 [23 18]] swaack first [popd] dip /
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[23 18] . size [41.0 [23 18]] swaack first [popd] dip /
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[23 18] . 0 swap [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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[23 18] 0 . swap [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 [23 18] . [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 [23 18] [pop ++] . step [41.0 [23 18]] swaack first [popd] dip /
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0 23 [pop ++] . i [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 23 . pop ++ [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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0 . ++ [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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1 . [18] [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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1 [18] . [pop ++] step [41.0 [23 18]] swaack first [popd] dip /
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1 [18] [pop ++] . step [41.0 [23 18]] swaack first [popd] dip /
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1 18 [pop ++] . i [41.0 [23 18]] swaack first [popd] dip /
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1 18 . pop ++ [41.0 [23 18]] swaack first [popd] dip /
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1 . ++ [41.0 [23 18]] swaack first [popd] dip /
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2 . [41.0 [23 18]] swaack first [popd] dip /
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2 [41.0 [23 18]] . swaack first [popd] dip /
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[23 18] 41.0 [2] . first [popd] dip /
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[23 18] 41.0 2 . [popd] dip /
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[23 18] 41.0 2 [popd] . dip /
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[23 18] 41.0 . popd 2 /
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41.0 . 2 /
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41.0 2 . /
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20.5 .
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Replacing ``size`` with a Python Version
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Both ``sum`` and ``size`` each convert a sequence to a single value.
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::
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sum == 0 swap [+] step
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size == 0 swap [pop ++] step
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An efficient ``sum`` function is already in the library. But for ``size`` we can use
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a "compiled" version hand-written in Python to speed up evaluation and make the trace more readable.
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.. code:: ipython2
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from joy.library import SimpleFunctionWrapper
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from joy.utils.stack import iter_stack
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@SimpleFunctionWrapper
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def size(stack):
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'''Return the size of the sequence on the stack.'''
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sequence, stack = stack
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n = 0
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for _ in iter_stack(sequence):
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n += 1
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return n, stack
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Now we replace the old version in the dictionary with the new version,
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and re-evaluate the expression.
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.. code:: ipython2
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D['size'] = size
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A Shorter Evaluation
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~~~~~~~~~~~~~~~~~~~~
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You can see that ``size`` and ``sum`` now execute in a single step.
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.. code:: ipython2
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V('[23 18] average')
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.. parsed-literal::
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. [23 18] average
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[23 18] . average
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[23 18] . [sum 1.0 *] [size] cleave /
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[23 18] [sum 1.0 *] . [size] cleave /
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[23 18] [sum 1.0 *] [size] . cleave /
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[23 18] [sum 1.0 *] [size] . [i] app2 [popd] dip /
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[23 18] [sum 1.0 *] [size] [i] . app2 [popd] dip /
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[23 18] [[sum 1.0 *] [23 18]] [i] . infra first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [sum 1.0 *] . i [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] . sum 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 . 1.0 * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41 1.0 . * [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 . [[23 18]] swaack first [[size] [23 18]] [i] infra first [popd] dip /
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41.0 [[23 18]] . swaack first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] [41.0] . first [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 . [[size] [23 18]] [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] . [i] infra first [popd] dip /
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[23 18] 41.0 [[size] [23 18]] [i] . infra first [popd] dip /
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[23 18] [size] . i [41.0 [23 18]] swaack first [popd] dip /
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[23 18] . size [41.0 [23 18]] swaack first [popd] dip /
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2 . [41.0 [23 18]] swaack first [popd] dip /
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2 [41.0 [23 18]] . swaack first [popd] dip /
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[23 18] 41.0 [2] . first [popd] dip /
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[23 18] 41.0 2 . [popd] dip /
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[23 18] 41.0 2 [popd] . dip /
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[23 18] 41.0 . popd 2 /
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41.0 . 2 /
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41.0 2 . /
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20.5 .
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