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Lexical rules are formulated in the form of lex_rule/2
predicates. These rules, which represent redundancies in the lexicon,
operate on a subset of the items in the lexicon modifying their
categories and/or their phonology/spelling. There are two lexical rule
packages: one that belongs to ALE, and another that comes with the
TRALE extension. This section deals with ALE lexical rules,
which have the following format:
<RuleName> lex_rule <RewriteRule> morphs <MorphologicalRule>.For more information on the syntax of lexical rules, refer to the user's guide.
During compilation, the predicate lex_rule/8 is called, when
appropriate, to close the lexicon under the available lexical rules.
This process simply involves threading together the input and output
descriptions with procedural attachments and the phonological mapping
rules if they are specified. Phonological mapping rules are handled by
morph/3. More specifically, morph(Morphs,WordIn,WordOut)
converts WordIn to a list of characters; then it calls
morph_chars/3 to apply a pattern specified in Morphs, and
finally it converts the resulting character list back to a word
unifying it with WordOut. If Morphs contains more than one
pattern, morph_chars/3 uses the first one that applies and
succeeds.