reads a term from a stream and retrieves information about variables.

read_term (-Term, +Options)
read_term (+Stream, -Term, +Options)

read_term/2 reads from the current inputstream a single term(Term).
read_term/3 reads from the given stream(Stream) a single term(Term).
If the end of the stream is reached, Term will be unified with the atom end_of_file.

Elements of the Options-list can be:

variables(-Vars)
variable_names(-VarList)
singletons(-VarList)

Arguments

Stream                 text input stream
Term                   term
Options                list of options

Examples

?- open('test.data', write, Stream),
   write(Stream, 'member(X, [X|L]).\n'),
   close(Stream).

?- open('test.data', read, Stream),
   read_term(Stream, Term, [variable_names(VarNames),singletons(Singletons)]).

Term        = member(_1, [_1|_2])
VarName     = ['X' = _1, 'L' = _2]
Singletons  = ['L' = _2]

Standard

These predicates are part of the ISO-Prolog Standard.

See also