LD-PRE-EVAL-FILTER.html -- ACL2 Version 6.3

## LD-PRE-EVAL-FILTER

determines which forms `ld` evaluates

    Major Section:  MISCELLANEOUS

`Ld-pre-eval-filter` is an `ld` special (see ld). The accessor is `(ld-pre-eval-filter state)` and the updater is `(set-ld-pre-eval-filter val state)`. `Ld-pre-eval-filter` must be either `:all`, `:query`, or a new name that could be defined (e.g., by `defun` or `defconst`). The initial value of `ld-pre-eval-filter` is `:all`.

The general-purpose ACL2 read-eval-print loop, `ld`, reads forms from `standard-oi`, evaluates them and prints the result to `standard-co`. However, there are various flags that control `ld`'s behavior and `ld-pre-eval-filter` is one of them. If the filter is `:all`, then every form read is evaluated. If the filter is `:query`, then after a form is read it is printed to `standard-co` and the user is asked if the form is to be evaluated or skipped. If the filter is a new name, then all forms are evaluated until that name is introduced, at which time `ld` terminates normally.

The `:all` filter is, of course, the normal one. `:Query` is useful if you want to replay selected the commands in some file. The new name filter is used if you wish to replay all the commands in a file up through the introduction of the given one.