forge-formula.md
In hardhat: Construct Modeling Packages

can be both missing levels and have new levels

Code
  mold(y ~ f, dat, blueprint = bp2)
Condition
  Error in `recompose()`:
  ! `data` must only contain numeric columns.
  i These columns aren't numeric: "f".

`allow_novel_levels` works right with character predictors

Code
  out <- forge(df2, x$blueprint)
Condition
  Warning:
  Novel levels found in column 'x': 'd'. The levels have been removed, and values have been coerced to 'NA'.