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Predicate atomic_list_concat/2
Availability:built-in
[commons]atomic_list_concat(+List, -Atom)
List is a list of strings, atoms, integers, floating point numbers or non-integer rationals. Succeeds if Atom can be unified with the concatenated elements of List. Equivalent to atomic_list_concat(List,’’, Atom).

Examples

?- atomic_list_concat([a, 42], X).
X = a42.
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LogicalCaptain said (2020-05-02T07:51:06):0 upvotes 0 0 downvotes
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Your choices

Your choice of predicate is as follows:

Two concatenable terms as input (can split)

Two more general concatenable terms as input (cannot split because arguments 1 and 2 are too general)

A list of concatenable terms as input (never split)

  • atomic_list_concat/2 - generates atom at argument 2. Refuses string at argument 2 in accept mode (that's likely a bug).
  • atomics_to_string/2 - generates string at argument 2. Refuses atom at argument 2 in accept mode (that's likely a bug).

A list of concatenable terms as input, and intersperse another string (can split at interspersed string)

  • atomic_list_concat/3 - concatenate with separator ("intersperse", "join"). Refuses string at argument 3 in accept mode (that's likely a bug).
  • atomics_to_string/3 - concatenate with separator ("intersperse", "join"). Refuses atom at argument 3 in accept mode (that's likely a bug).

Test code

:- begin_tests(atomic_list_concat).

test("atom_list_concat/2 always generates atom at the 3rd argument from any list-of-atomics") :-
   atomic_list_concat([a,b],X1),
   assertion(X1==ab),
   atomic_list_concat(["a","b"],X2),
   assertion(X2==ab),
   atomic_list_concat([a,"b",12],X3),
   assertion(X3==ab12).

test("atom_list_concat/3 in 'accept mode' (as expected) allows atomics in the list") :-
   atomic_list_concat(["a",b],ab),
   atomic_list_concat(["a",12,b],a12b).

test("atom_list_concat/3 in 'accept mode' (surprisingly) disallows string for argument 2",fail) :-
   atomic_list_concat(["a",b],"ab").

test("atom_list_concat/3 edge case works as expected") :-
   atomic_list_concat([],X1),
   assertion(X1==''),
   atomic_list_concat([''],X2),
   assertion(X2==''),
   atomic_list_concat(['',''],X3),
   assertion(X3==''),
   atomic_list_concat([""],X4),
   assertion(X4==''),
   atomic_list_concat(["",""],X5),
   assertion(X5=='').
   
test("atom_list_concat/3 refuses to generate",error(instantiation_error)) :-
   atomic_list_concat([a,_X,c],abc).
   
:- end_tests(atomic_list_concat).