- STRUCTURE
- SYNOPSIS
Tests a term to see if it is an implication or a negation.
- DESCRIPTION
If M has the form t1 ==> t2, or the form ~t, then is_imp M
returns true. If the term is neither an implication nor a negation
the result is false.
- FAILURE
Never fails.
- COMMENTS
Yields true of negations because dest_imp destructs negations (for
backwards compatibility with PPLAMBDA). Use is_imp_only if you don’t want
this behaviour.
- SEEALSO