* Change alias shape inference to proposal of RFC#4
* Remove commented code
* Fix typo
* Change comment to be more informative
* Make match statement to lookup in table
* Remove resolved question
https://github.com/nushell/nushell/pull/2685#discussion_r509832054
* Pick ...or_insert_dependency functions into pieces
Previously there was get_shape_of_expr_or_insert dependency, now there is
get_shape_of_expr and get_shape_of_expr_or_insert_dependency
2 new functions have been added: get_result_shape_of_math_expr and
get_result_shape_of_math_expr_or_insert_dependency
* Remove flattening of deep binary expressions
Previously deep binary expressions have been flattened through the insertion of
fake vars. This logic was quite complicated. Now if a variable depends on the
result shape of a binary expression and the result shape can't be computed,
the variable simply depends on the whole binary.
* Change Expression::Variable(Variable::It(...)) to Expression::Variable(...)
* Simplify get_result_shapes_in_math_expr
* Simplify infer_shapes_in_binary_expr
* Clarify comment
* Clarify comment
* Fix clippy lint
* Move check for real var into checked_insert
* Remove comment
* Rename var
* figuring out error with lines
* make progress in printing of block
* support for external commands; fix some tiny bugs in formatting
* basic printing of block; going to experiment with bubbling raw input to the command itself to avoid potential edge cases
* remove fmt::Display impls for hir structs; bubbled raw_input to command args
* compiling checkpoint :)
* process raw input alias to remove save flag; do duplicates stored
* fix warnings; run clippy
* removed tmux log file
* fix bug in looking for same alias; changed unwraps to safe unwraps
