I’ve recently begin learning to code in Haskell — in general all is going well, but one irritation that repeatedly rears its head is ghci not recognizing modules on hackage when I try to use them.
Some modules work fine — Data.List.subsequences (for example) returns all sublists of a list as desired:
Others seem more problematic — Data.NumberLength goes completely unrecognized:
I haven’t explicitly downloaded or installed anything in terms of modules, but my (rudimentary) understanding from the GHCup home page together with the introduction from Learn You a Haskell is that ghci can handle fetching and importing any modules I need for the code I try to write.
What am I doing wrong here?
