[Haskell-beginners] Resources to learn functional programming

Hi everyone, I'm fairly new to Haskell. I'm trying to learn it, but got stuck when i reached high-order functions. I understand what they are, but I cannot wrap my head on how they work, how to use them, and such. It seems so abstract to me. I tried to move on past it, but it only got harder and harder. Looks like I have problems learning functional programming. Do you have any good resources to learn functional programming? I am a decent C++ programmer. Thanks. Homero Cardoso de Almeida