local syntax_option(++Option)

export syntax_option(++Option)

set_flag(syntax_option, ++Option)

Option

an atom or a term not(Atom)

Description

An option Option is selected via syntax_option(Option) and unselected via syntax_option(not(Option)).

Options can be declared as local to the contect module, or exported.

The following options are available:

atom_subscripts

allow atoms to be followed by subscripts, and parse as subscript/2. Useful for parsing other languages, e.g. FlatZinc.

bar_is_no_atom

disallow the use of an unquoted vertical bar as atom or functor, except when it occurs in infix-position.

bar_is_semicolon

translate occurrences of unquoted infix vertical bars into terms with functor ;/2, e.g. (a|b) = (a;b).

based_bignums

Allow base notation even for integers longer than the wordsize (i.e. they are always positive).

blanks_after_sign

ignore blank space between a sign and a number (by default, this space is significant and will lead to the sign being taken as prefix operator rather than the number's sign). Also allow signs of numbers to be quoted.

blanks_in_nil

has no effect (obsolete).

curly_args_as_list

Parse terms written as {a,b,c} as {}([a,b,c]) instead of the default {}((a,b,c)).

dense_output

If set, all predicates of the write-family will print terms with the spacing(compact) option by default, otherwise spacing(generous).

doubled_quote_is_quote

parse a pair of quotes within a quoted item as one occurrence of the quote within the item. If this option is off (the default), consecutive string-quoted and list-quoted items are parsed as a single (concatenated) item, while consecutive quoted atoms are parsed as consecutive atoms.

eof_is_no_fullstop

do not treat end-of-file as a fullstop.

float_needs_point

require floating point numbers to be written with a decimal point, e.g. 1.0e-3 instead of 1e-3.

general_subscripts

allow atoms, parenthesized subterms and subscripted subterms to be followed by subscripts, and parse as subscript/2. Useful for parsing other languages, e.g. Zinc.

iso_base_prefix

allow binary, octal or hexadecimal numbers to be written with 0b, 0o or 0x prefix respectively, and disallow the base'number notation.

iso_escapes

ISO-Prolog compatible escape sequences within strings and atoms.

iso_restrictions

enable all ISO-Prolog syntax restrictions that are not controlled by individual settings. This includes: disallowing operators as operands of operators; disallowing an atom to be declared as both an infix and a postfix operator; restrictions on changing operator properties for comma, vertical bar, and the empty-bracket atoms.

limit_arg_precedence

do not allow terms with a precedence higher than 999 as structure arguments, unless parenthesised.

nested_comments

allow bracketed comments to be nested.

nl_in_quotes

allow newlines to occur inside quotes (default).

no_array_subscripts

do not allow array subscript syntax for subscript/2.

no_attributes

disallow the Eclipse specific syntax for variable attributes in curly braces.

no_blanks

do not allow blanks between functor and opening parenthesis (default).

no_curly_arguments

disallow the Eclipse specific syntax for structures with named arguments in curly braces.

no_string_concatenation

do not parse consecutive string literals as a single (concatenated) string.

plus_is_no_sign

do not interpret a plus sign preceding a number as the number's sign (effectively ignoring it), but treat it as a possible prefix operator +/1.

read_floats_as_breals

read all floating point numbers as bounded reals rather than as floats. The resulting breal is a small interval enclosing the true value of the number in decimal notation.

syntax_errors_fail

the predicates of the read-family fail when encountering a syntax error (after printing an error message). Without this option, the predicates throw an error term of the form error(syntax_error(MessageString),context(...)).

var_functor_is_apply

allow variables as functors, and parse a term like X(A,B,C) as apply(X,[A,B,C]).

Modes and Determinism

• syntax_option(++) is det

See Also