Begin to split op1 into op1 and op1Effect.
add Op1Effect
Finish splitting Op1 and Op1Effect nodes.
.
revert to the original version, no split of op1_effect
merge master into current branch
add build_graph function
Code walkthrough/fixes
build graph on all cases
add const folding
From meeting.
fix syntax errors; add function to optimize GetAttr
add op1 op2 in constant folding
add todo
merge
add const folding in command-line; simplify the op1 and op2 evalution
add substitution
let should only bind var with const; add object eval
add const propagation
fix binding bugs