Context Errors

A context error occurs when a goal or declaration appears in the wrong place. There may or may not be anything wrong with the goal or declaration as such; the point is that it is out of place. Calling multifile/1 as a goal is a context error, as is having :-module/2 anywhere but as the first term in a source file.

The exception code associated with a context error is

     context_error(Goal, ContextType, CommandType)
     

ContextType

the context in which the command was attempted.

Some ContextTypes recognized by the system include:

• 'pseudo-file ''user''' -- for pseudo-file 'user'
• if -- inside an if
• bof -- at beginning of file
• bom -- at beginning of module
• query -- in query
• before -- before
• 'after clauses' -- after clauses
• 'not multifile and defined' -- for defined, non-multifile procedure
• 'static multifile' -- for static multifile procedure.
• language(L) -- for language L.
• file_load -- during load of file(s).
• started -- started up
• notoplevel -- when no top level

CommandType

the type of command that was attempted.

Some CommandTypes recognized by the system include:

• 0 -- no commandtype specified
• cut
• clause
• declaration
• 'meta_predicate declaration'
• use_module
• 'multifile assert'
• 'module declaration'
• 'dynamic declaration'
• meta_predicate(M) -- meta_predicate declaration for M
• argspec(A) -- Invalid argument specification A
• foreign_file(File) -- foreign_file/2 declaration for File
• foreign(F) -- foreign/3 declaration for F
• (initialization) -- initialization hook
• abort -- call to abort/0