Summary:
Prevent returning a negative cost bound when calling `substring(begin_index, end_index)` when either is possible
- `begin_index < 0`
- `begin_index > end_index`
Instead, return unit cost since such cases either throw `IndexOutOfBoundsException ` at runtime or correspond to having two symbolic bounds that cannot be semantically compared.
Reviewed By: dulmarod
Differential Revision: D19619410
fbshipit-source-id: cf5e8cb7b
Summary: `cost.ml` is huge. Let's split it to its logical parts (basically creating new files for the modules that were already in `cost.ml`) and move all cost related files into `\cost` directory. While we are at it, let's add `mli` files too.
Reviewed By: jvillard
Differential Revision: D19496263
fbshipit-source-id: 45096db4c
Sungkeun Cho
Ezgi Çiçek