- For
`write`

and`writeq`

, the term is written with respect to current operator declarations (See ref-syn-ops for a discussion of operators).`write_canonical(`

`Term``)`

writes`Term`to the current or specified output stream in standard syntax (see ref-syn on Prolog syntax), and quotes atoms and functors to make them acceptable as input to`read/[1,2]`

. That is, operator declarations are not used and compound terms are therefore always written in the form:`predicate_name`(`arg1`, ...,`argn`) - Atoms output by
`write/[1,2]`

cannot in general be read back using`read/[1,2]`

. For example,| ?-

`write('a b').`a bIf you want to be sure that the atom can be read back by

`read/[1,2]`

, you should use`writeq/[1,2]`

, or`write_canonical/[1,2]`

, which put quotes around atoms when necessary, or use`write_term/[2,3]`

with the`quoted`

option set to`yes`

. Note also that the printing of quoted atoms is sensitive to character escaping (see ref-syn-ces). `write/[1,2]`

and`writeq/[1,2]`

treat terms of the form`'$VAR'(`

`N``)`

specially: they write ‘`A`’ if`N`=0, ‘`B`’ if`N`=1, ...‘`Z`’ if`N`=25, ‘`A1`’ if`N`=26, etc. Terms of this form are generated by`numbervars/3`

(see ref-lte-anv). Terms of the form`'$VAR'(`

`X``)`

, where`X`is not a number are written as unquoted terms. For example,| ?-

`writeq(a('$VAR'(0),'$VAR'('Test'))).`a(A,Test)`write_canonical/1`

does*not*treat terms of the form`'$VAR'(`

`N``)`

specially. It writes square bracket lists using`./2`

and`[]`

(that is,`[a,b]`

is written as ‘`.(a,.(b,[]))`’).

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