Tracing Joy Execution

joy.utils.pretty_print

Pretty printing support, e.g.:

Joy? 23 18 * 99 +
       . 23 18 mul 99 add
    23 . 18 mul 99 add
 23 18 . mul 99 add
   414 . 99 add
414 99 . add
   513 . 

513 <-top

joy? 

On each line the stack is printed with the top to the right, then a . to represent the current locus of processing, then the pending expression to the left.

class joy.utils.pretty_print.TracePrinter

This is what does the formatting. You instantiate it and pass the viewer() method to the joy.joy.joy() function, then print it to see the trace.

go()

Return a list of strings, one for each entry in the history, prefixed with enough spaces to align all the interpreter dots.

This method is called internally by the __str__() method.

Return type:list(str)

viewer(stack, expression)

Record the current stack and expression in the TracePrinter’s history. Pass this method as the viewer argument to the joy.joy.joy() function.

Parameters:

• quote (stack) – A stack.
• expression (stack) – A stack.