Why is it correct to say (2) but not (1)
(1) You are here "for learning" English.
(2) You are here "to learn" English.
Why is it correct to say (2) but not (1)
(1) You are here "for learning" English.
(2) You are here "to learn" English.
(2) "to learn" is correct because it expresses the purpose. It answers the question "why".
Question: Why are you here?
Answer: To learn XYZ.
Speakers of Romance languages such as Italian, express purpose using the preposition per which is also translatable as "for", but in English saying why something is done is normally expressed using the infinitive. The construction "for + V+ing" is often used when referring to a tool and its function.
A: What was this object used for?
B It was used for opening envelopes
An explanation might be shorter than even in higly esteemed Mr. Michael Swan's practical guidebook: because there is no any other prepositional phrase for substitution of the prepositional phrase with "so as to" or "in order to" as a Head word ,or just an infinitive, for any purpose clause.
E.g. I am here (Principal clause) to learn ( that is the substitute for a Subordinate Clause, being the Purpose Clause in the sentence in standard form "so as to learn"or"in order to learn" ).
You could see easily that in the sentence Is that cake for eating or just for looking at? (an example from Michael Swan's manual) the Preposition Phrase with For is a Subject Complement but not a substitute for a Purpose Clause. The same relates to the example An altimeter is used for measuring height above sea level., where the Prepositional Phrase with For is the Prepositional Complement of the Predicate in the sentence.
In respect to the sentence You are here for learning English, it might be taken as You are here (Principal Clause) and for learning English (the Subordinate Clause of Reason).
But, in such reading are many grammatical inconsistences. There is no such a Prepositional Phrase with the preposition For to substitute the Subordinate Clause of Purpose. Such case need the prepositional phrase with the prepositions As or As For. E.g. I am here as for learning English. That is why such sentence with preposition For is counted as a bit ungrammatical and open to question, or informal, when it concerns a person.
The widely known sentence Is going back to school for teaching right for you? is an example of the intentional informal English usage used jokingly in the newspaper style.