moved batch-io test for xexpr at neu to manual mode
allow universe handlers to return state of universe, nt just bundle
allow universe handlers to return state of universe, not just bundle
allow universe handlers to return state of universe, not just bundle
added history to modified handlers
added secret state code for Oliver
improve magic opening square bracket for for/fold
testing
Revert "fix a bug in f669c47c1"

This reverts commit 379ed6b46e1a7d2108ea619f5f2fb74ac9a0609e.

Stupid robby experiment
Revert "Revert "fix a bug in f669c47c1""

This reverts commit 2e29a180397be476a6e5647d43291a8f05391943.

Reverted the wrong commit.
Revert "testing"

This reverts commit 6ccfbec2b927efe28a039cf154097702fc325212.
Add links to videos, and add links to slides/code in the schedule.
2htdp/universe: adjust universe `loop` to make it a loop

Neither the body nor handler functions in `with-handlers` are
in tail position with respect to `with-handlers`.
2htdp/universe: adjust world `loop` to make it a loop

Similar to the server-side problem, but on the client side. In a
game where the server drives the clients with frequent messages
through `on-tick`, per-message growth in the continuation can
matter a lot.
add pattern-expanders to syntax/parse
move pattern-expander contracts to outer modules, trim exports

This avoids mysterious errors later in the build process related to
TR and static-contracts. I don't see how the pattern-expander code
could possibly cause the errors that occur, but this commit fixes them.
update docs for syntax pattern expanders
Add Neil's slides.
redex: make the depth-based clause ordering smarter
redex: try harder when checking non-terminals

Unfold non-terminals other than the one we're currently
checking, and follow variable references, when normalizing
patterns for nt checking.