display the type-alist from the current context
Major Section: PROOF-CHECKER-COMMANDS
Examples: (type-alist t t) ; display type-alist based on both conclusion and governors type-alist ; same as (type-alist nil t) -- governors only (type-alist nil) ; same as (type-alist nil t) -- governors only (type-alist t) ; same as (type-alist t nil) -- conclusion only (type-alist nil nil) ; display type-alist without considering ; conclusion or governorswhere if
General Form: (type-alist &optional concl-flg govs-flg)
govs-flgis omitted, it defaults to
Display the current assumptions as a type-alist. Note that this display includes the result of forward chaining.
There are two basic reasons contemplated for using this command.
1. The theorem prover has failed (either outside the proof-checker or using a
proof-checker command such as
reduce and you want to
debug by getting an idea of what the prover knows about the context.
a. You really are interested in the context for the current term. Include hypotheses and governors (i.e., accounting for tests of surrounding
if-expressions that must be true or false) but not the current conclusion (which the theorem prover's heuristics would generally ignore for contextual information). Command:
(type-alist nil t); equivalently,
b. You are not thinking in particular about the current term; you just want to get an idea of the context that the prover would build at the top-level, for forward-chaining. Incorporate the conclusion but not the governors. Command:
(type-alist t nil); equivalently,
2. You intend to use one of the proof-checker-commands that does
simplification, such as
x, and you want to see the context.
Then include the surrounding
if-term governors but not the goal's
(type-alist nil t) ; equivalently,
See type-set (also see type-prescription) for information about
ACL2's type system, which can assist in understanding the output of the