term_chars/2

Module: builtins

term_chars/2 — convert between a term and the list of characters which represent the term
term_codes/2 — convert between a term and the list of character codes which represent the term

FORMS

term_chars(Term, CharList)

term_codes(Term, CodeList)

DESCRIPTION

If CharList is bound to a list of characters then it is parsed according to the syntax rules for terms. Should the parse be successful, the resulting value is unified with Term in a call to term_chars/2.

If CodeList is bound to a list of character codes then it is is parsed according to the syntax rules for terms. Should the parse be successful, the resulting value is unified with Term in a call to term_codes/2.

Otherwise CharList (or CodeList) will be bound to the list of characters (character codes) which would result as output from write_canonical(Term).

EXAMPLES

?- term_chars(p(a,X), L).
X = X
L = [p,'(',a,',','_','A',')']
yes.

?- term_codes(A,"X = /* a comment */ 3+4").
A = (_A = 3+4)
yes.

?- term_codes(A,"foo bar").
Error: Syntax error.
- Goal: builtins:term_codes(_A,"foo bar")
- Error Attribute: syntax('foo barend_of_file\n ^',
'Fullstop (period) expected',1,
stream_descriptor('',closed,string,
string("foo bar"),[input|nooutput],false,3,
[],0,0,0,true,1,wt_opts(78,40000,flat),[],
true,text,eof_code,0,0))
- Throw pattern: error(syntax_error,
[builtins:term_codes(_A,*),
syntax('foo barend_of_file\n ^',
'Fullstop (period) expected',1,
stream_descriptor('',closed,string,*,*,
false,3,[],0,0,0,true,1,*,[],true,
text,eof_code,0,0))])

ERRORS

CharList is bound to a list, but the list does not contain characters

– – – – > domain_error(character_list, CharList)

CodeList is bound to a list, but the list does not contain character codes

– – – – > domain_error(character_code_list, CodeList)

CharList (or CodeList) is not parsable as a term

– – – – > syntax_error