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 | Predicate portray_text/1 |
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[det]portray_text(+OnOff:boolean)true, consider lists of
integers as list of Unicode code points and print them as corresponding
text inside quotes: `text` or "text". Quoting
depends on the value of current_prolog_flag/2 back_quotes.
Same as
?- set_portray_text(enabled, true).
Examples
Use append/3 for substitution in a list
Use append/3 for substitution in a list
The append/3 predicate can be used to split and join lists. We can combine that to realise substituting all appearances of a sublist into another as illustrated below.
append(This, After, Rest)creates a pattern from This, i.e., the list Rest starts with This.append(Before, Rest, MyStr)matches the pattern against the input list. On a match we commit (!). Now Before is the input list before the match and After is the input list after the match.- Recursively replace in After
- Join the parts.
subst(This, That, MyStr, Result) :-
append(This, After, Rest),
append(Before, Rest, MyStr),
!,
subst(This, That, After, AfterResult),
append([Before,That,AfterResult], Result).
subst(_, _, S, S).
?- portray_text(true). true. ?- subst(`this`,`that`,`athishellothis`,R). R = `athathellothat`.