Here's the GHC docs on "packages": https://downloads.haskell.org/~ghc/8.4.1/docs/html/users_guide/packages.html tl;dr a package is a bundle of modules. Packages are installed into a ghc package database. (Stack manages ghc package databases for you.) "dependencies" generally refers to any other packages required to build a given project or package. For more info on "packages" and "projects" (with regards to stack), see https://docs.haskellstack.org/en/stable/stack_yaml_vs_cabal_package_file/#pa... A "Stackage snapshot" is a collection of packages, where each package is pinned to a specific version of that package. https://docs.haskellstack.org/en/stable/stack_yaml_vs_cabal_package_file/#re... https://docs.haskellstack.org is generally the place to go for info like this. And of course, if you have any questions, you're welcome to ask them here, or on the haskell-stack mailing list: https://groups.google.com/forum/#!forum/haskell-stack -- Dan Burton On Sat, Apr 7, 2018 at 12:53 PM, Dennis Raddle wrote:

Now I'm trying to use stack to install and run GCHJS. Can someone help me figure out this error?

I first created project 'proj01' using the ghcjs template via

stack new proj01 ghcjs

Then I typed

stack build

It ran for a while, then gave an error messages that starts

"While building custom Setup.hs for package semigroupoids-5.0.0.4 using .... <very long description>, Process exited with code ExitFailure 1"

But it didn't halt. Instead it started compiling Main.hs, and ended up saying

"at least the following dependencies are missing: tagged >= 0.8.5 && <1 && ==0.8.1"

I tried adding "tagged" to the extra-deps in the stack.yaml, but it didn't help.

While I'm posting, is there a resource that explains background to this? I don't know much about "packages," "snapshots," "dependencies", means of specifying versions, cabal, or YAML files. Everything I find online seems to assume some background knowledge of these things. For instance the stack documentation talks about snapshots, but I can't find an explanation that I understand for what a "snapshot" actually is. Ditto for all these many concepts that go into configuring and building.

D

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