optimal_stack
I don't think the heap implementation is mine, but I don't remember where it's from. Let me know if you find it so I can put the right license.
Compiler for stack manipulation in Michelson
A lot of operations in Michelson are stack manipulation operations that decompose structures on the stack and recompose them. This is a compiler that calculates the optimal sequence of stack operations to achieve a given result using A*.
This could be used as a light compilation pass for a JUMBLE macro that would work like this:
JUMBLE (a,b):c:(d,(e,f)) => (a,f):(c,d)
Would turn a stack of the form on the left into a stack of the form on the right. a,b,c,d,e,f are symbolic variables.
Currently, this compiler is quite slow because it attempts to find the optimal solution. Here are ways in which it could be made practical
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Instead of searching for an optimal solution among the graph of all stack manipulations, start from a known admissible solution and refine it using a set of rewriting rules.
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Speed up the seach by
- introducing more theorems about minimal costs in order to improve the A* heuristic
- adding pseudo-instructions with known costs in order to help guide the search