I am not sure whether the reason I previously failed Haskell is

1. Because it's actually hard
2. Because of a mental block caused by failing at it more than once already
3. Because Haskell users are really bad at explaining things

I think it's a little 2 and mostly 3. I *love* ML, I know two MLs (3 if you count Rust) plus have in the past written my own ML. I understand the parts of Haskell that are just ML and get lost whenever I hit "do"— the point of divergence from ML; the dreaded Monad.

In the Haskell docs

https://wiki.haskell.org/Haskell_in_5_steps

It states this is how you build a Haskell program to run it.

Assuming I realize I can drop -threaded, is actually the easiest/correct way to build a Haskell program to run in the year 2025?

I run the given ghc --make command. It leaves some crap in src/. Say I do not want intermediate files in my source tree. I would like them to be moved to bin/ or obj/ or something, or simply not retained. Is this possible, or is Haskell in 2025 simply a "leaves crap in src/" kind of language in 2025?

I found -no-keep-hi-files and -no-keep-o-files (despite them technically not being documented) but say I want to retain them, just in a place of my choosing.

I am attempting to call "openFile" on the first command line argument in Haskell¹. It doesn't like it.

I'm not sure I'm looking at the right docs. I searched Google for "haskell system.io" and got https://hackage.haskell.org/package/base-4.21.0.0/docs/System-IO.html#v:openFile . I don't know if this is the newest Haskell2010 or if $GOOG is confused.

The doc (every doc I find) claims the type of openFile is FilePath -> IOMode -> IO Handle. But hls on my computer seems to think it's FilePath ->IOMode -> Bool -> IO Handle. Am I missing something?

Haskell people, please help me.
There are 3 image attachments to this post, showing the same code block but with different amounts of indentation.

The first code block works,
the second block does not work,
the third one REALLY does not work.

According to my editor, none of these blocks of code contains tabs.

Haskell appears (?) to treat three spaces, four spaces, and eight spaces radically differently.

I dislike multiple-of-3 indents.

What do I need to read to understand what I am missing?

@mcc only in the first case is the "let" keyword (and following code) aligned to "do"

It's just significant whitespace. You can either align everything on the column after "do " (that's where the 3 chars come from) or indent on a newline with an indent width of your choice.