Section "atom"

We make the content of a host language string, which is also our datatype of a Prolog atom visible as a list of Unicode points. The string encoding of the host language is made transpar-ent. The built-ins do not expose the string encoding. This translates also to the Prolog characters codes and atoms used by streams in the next section.

The following atom built-ins are provided:

atom_codes(A, L): [ISO 8.16.5]

If A is a variable, the built-in succeeds in A with the for the Prolog list L. Otherwise the built-in succeeds in L with the Prolog list from the atom A.

char_code(C, N): [ISO 8.16.6]

If C is a variable, the built-in succeeds in C with the character for the code N. Otherwise the built-in succeeds in N with the code from character C.

atom_number(A, N):

If A is a variable, then the built-in succeeds in A with the atom for the Prolog number N. Otherwise the built-in succeeds in N with the Prolog number from the atom A.

atom_integer(A, R, N):

If A is a variable, then the built-in succeeds in A with the atom for the Prolog integer N in radix R. Otherwise the built-in succeeds in N with the Prolog number from the atom A in radix R.

atom_reference(A, R):

The built-in succeeds in A with the atom for the Prolog reference R.

atom_length(X, Y): [ISO 8.16.1]

The predicate succeeds in Y with the length of the atom X.atom_concat(X, Y, Z): [ISO 8.16.2]
The built-in succeeds when Z is the concatenation of X and Y.

sub_atom(X, Y, Z, T, U): [ISO 8.16.3]

The predicate succeeds whenever the atom U is the sub atom of the atom X starting at position Y with length Z and ending T characters before.

last_sub_atom(X, Y, Z, T, U):

The predicate succeeds whenever the atom U is the sub atom of the atom X starting at position Y with length Z and ending T characters before.

atom_join(L, A):

The built-in succeeds in A with the join of the atoms L.

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