# Internal representation (IR) development

## Expression types

- [x] Bool
- [x] Int
- [x] Float
- [x] Binary
- [x] Range
- [x] Var
- [x] VarDecl
- [x] unexpected error outside of `let`
- [x] Call
- [x] ExternalCall
- [x] Operator
- [x] unexpected error outside of `BinaryOp`
- [x] RowCondition
- [x] UnaryNot
- [x] BinaryOp
- [x] Subexpression
- [x] Block
- [x] Closure
- [x] MatchBlock
- [x] in `match`
- [x] unexpected error outside of `match`
- [x] List
- [x] Table
- [x] Record
- [x] Keyword
- [x] unexpected error
- [x] ValueWithUnit
- [x] DateTime
- [x] Filepath
- [x] Directory
- [x] GlobPattern
- [x] String
- [x] RawString
- [x] CellPath
- [x] FullCellPath
- [x] ImportPattern
- [x] as parser info
- [x] unexpected error
- [x] Overlay
- [x] as parser info
- [x] unexpected error
- [x] Signature
- [x] (does nothing, handled by parser)
- [x] StringInterpolation
- [x] GlobInterpolation
- [x] Nothing
- [x] Garbage
- [x] garbage encountered error

## Keywords

- [x] `if`
- [x] `match`
- [x] `let`, `mut`
- [x] `const`
- [x] `try`
- [x] `loop`
- [x] `while`
- [x] `for`
- [x] `return`

## Misc. TODO

- [ ] Verify / test redirection behavior
- [x] Custom command block eval
- [x] ~~Generate block from `RowCondition` in parser, to support `where`~~
- [x] just use the block, it's already there
- [x] `timeit`
- [x] `metadata`
- [x] `export-env`
- [ ] Make all Nushell tests pass with IR
- [x] Environment variable for running tests with IR
- [ ] Replace parser info with enum (rather than using `Expression`)
- [ ] Spans are probably not correct yet
- [ ] Decide what to do about constant evaluation
- [ ] ~~Clean up declared variables when leaving block scope~~
- [ ] current evaluator doesn't do this, but we can quite easily
- [ ] revisit in the future because right now we just `gather_captures()` and create new variables vec anyway
- [ ] Unknown args (these are just positional)