atom_concat(X, Y, Z) succeeds if the name of atom Z matches the concatenation of the names of atoms X and Y.
Examples
Examples of when all three terms are atoms:
?- atom_concat(abc, def, abcdef).
yes
?- atom_concat(a, bcdef, abcdef).
yes
?- atom_concat(abcde, f, abcdef).
yes
?- atom_concat(abcdef, '', abcdef).
yes
?- atom_concat('', abcdef, abcdef).
yes
?- atom_concat('', '', '').
yes
?- atom_concat(ab, def, abcdef).
no
?- atom_concat(abc, ef, abcdef).
noExamples of when first term is a variable:
?- atom_concat(abc, X, abcdef).
X = def
yes
?- atom_concat(abcde, X, abcdef).
X = f
yes
?- atom_concat(a, X, abcdef).
X = bcdef
yes
?- atom_concat('', X, abcdef).
X = abcdef
yes
?- atom_concat(abcdef, X, abcdef).
X =
yesExamples of when second term is a variable:
?- atom_concat(X, def, abcdef).
X = abc
yes
?- atom_concat(X, f, abcdef).
X = abcde
yes
?- atom_concat(X, bcdef, abcdef).
X = a
yes
?- atom_concat(X, abcdef, abcdef).
X =
yes
?- atom_concat(X, '', abcdef).
X = abcdef
yesExamples of when third term is a variable:
?- atom_concat(abc, def, X).
X = abcdef
yes
?- atom_concat(a, bcdef, X).
X = abcdef
yes
?- atom_concat(abcde, f, X).
X = abcdef
yes
?- atom_concat(abcdef, '', X).
X = abcdef
yes
?- atom_concat('', abcdef, X).
X = abcdef
yes
?- atom_concat('', '', X).
X =
yesExamples of when first and second terms are variables:
?- atom_concat(X, Y, abcdef).
X =
Y = abcdef
yes;
X = a
Y = bcdef
yes;
X = ab
Y = cdef
yes;
X = abc
Y = def
yes;
X = abcd
Y = ef
yes;
X = abcde
Y = f
yes;
X = abcdef
Y =
yes
?- atom_concat(X, Y, a).
X =
Y = a
yes;
X = a
Y =
yes
?- atom_concat(X, Y, '').
X =
Y =
yesExamples when combination of term types cause failure:
?- atom_concat(X, Y, Z).
Expected an atom but got: VARIABLE with value: Z
?- atom_concat('', Y, Z).
Expected an atom but got: VARIABLE with value: Z
?- atom_concat(X, '', Z).
Expected an atom but got: VARIABLE with value: Z
?- atom_concat(a, b, c).
no
?- atom_concat(a, '', '').
no
?- atom_concat('', b, '').
no
?- atom_concat('', '', c).
no