Build fails on macOS

[devkat]

Haskell and PureScript newbie here; I ran into this problem when trying to build purescript-halogen-realworld, which failed due to #38. Any insights are greatly appreciated!

• macOS 10.15.5 (Catalina)
• cabal 3.2.0.0 (via homebrew)
• ghc 8.10.1 (via homebrew)

cabal build exe:zephyr   
Warning: Requested index-state2020-06-09T00:00:00Z is newer than
'hackage.haskell.org'! Falling back to older state (2020-06-08T22:11:02Z).
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: zephyr-0.3.0 (user goal)
[__1] trying: purescript-0.13.8 (dependency of zephyr)
[__2] next goal: base (dependency of zephyr)
[__2] rejecting: base-4.14.0.0/installed-4.14.0.0 (conflict: purescript =>
base>=4.11 && <4.13)
[__2] skipping: base-4.14.0.0, base-4.13.0.0 (has the same characteristics
that caused the previous version to fail: excluded by constraint '>=4.11 &&
<4.13' from 'purescript')
[__2] rejecting: base-4.12.0.0, base-4.11.1.0, base-4.11.0.0, base-4.10.1.0,
base-4.10.0.0, base-4.9.1.0, base-4.9.0.0, base-4.8.2.0, base-4.8.1.0,
base-4.8.0.0, base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1,
base-4.6.0.0, base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0,
base-4.3.1.0, base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0,
base-4.1.0.0, base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from
non-upgradeable package requires installed instance)
[__2] fail (backjumping, conflict set: base, purescript, zephyr)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: purescript, zephyr, base

For the record, a workaround is fixing the purescript version to 0.13.6 in purescript-halogen-realworld/package.json:

"purescript": "0.13.6"

[coot]

Which version of zephyr are you using? 0.3.0 should work just fine.

[coot]

You need to use ghc-8.6, newer versions are not yet supported by purescript, hence the error:

[__2] rejecting: base-4.14.0.0/installed-4.14.0.0 (conflict: purescript =>
base>=4.11 && <4.13)

ghc-8.6.5 comes with: base-4.12; The version ofb ase library (and a handful of other core libraries) is bound to a specific version of ghc. This page is useful to track this