Parse Variables Using DCG

Question

I am having trouble parsing sequences that begin with capital letters into variables using Prolog's DCG notation. For instance, if I have the string

f a X y Z X

and a DCG that parses this string, is there any way to parse each capitalized letter into a unique Prolog variable. E.g., parse Y to a variable and each X to a variable? The intended application would be to build the functor

T = f(a,X,y,Z,X)

via a DCG rule ending with the statement

{T =.. [Head|Args]}

score 3 · Answer 1 · answered Jun 14 '11 at 17:01

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If you are using capital letters as an atom, you have to surround them between single quotes. E.g. 'X' and 'Z'.

Otherwise, they will be considered as prolog variables.

answered Jun 14 '11 at 17:01

gusbro

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score 3 · Accepted Answer · answered Jun 14 '11 at 21:02

3

Maybe you are looking for term_to_atom/3:

?- term_to_atom(Term, 'f(a,X,y,Z,X)').
Term = f(a, _G304, y, _G306, _G304).

answered Jun 14 '11 at 21:02

Kaarel

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This is precisely the predicate I was looking for. Thanks. – emi Jun 15 '11 at 11:52

Parse Variables Using DCG

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