I have always had a huge issue with ば、と、たら.
I understand that they all mean "if..." I understand that と is something natural like:
彼女は彼に会うといつも嬉しくなります。- She gets happy if/when she sees him.
Would ば be okay too?
彼女は彼に会えば、嬉しくなります。- If she sees him, she gets happy.
Along with なら I could say:
彼女は彼に会うなら嬉しくなります。- If she sees him, she gets happy.
Along with たら:
彼女は彼に会ったら嬉しくなります。- She gets happy if sees him.
I understand that they might be able to be used all like that but can someone explain their differences? Textbooks make it confusing and a lot of other sites do too :(
In addition to Misako's great explanation, I wanted to add one more point that I learned about these subtleties.
I asked around to some other native speakers to get an idea of the nuance they feel.
Basically, ば and たら both leave the feeling of something being left off. So:
both leave the receiver wondering, "Well, if she doesn't meet him, how will she be? Will she be sad? Will she still be happy? Has something happened and now she's depressed, but seeing him would be the only thing to cheer him up?
This is just to support Misako's answer that と is for stating something that always happens, and feels the most natural for saying something like "If A, then B." The other two make it feel, "If A, then in this case B will happen, but it's not the only outcome."
It's definitely a difficult nuance for me to wrap my head around, so thanks for the good question. I feel like I learned more about it by investigating the answer.