error when running ghc with the plugin directly: Unknown type constructor Nat, tests/pos/GCD.hs

[jwaldmann]

$ /opt/ghc/ghc-9.8.1/bin/ghc -fforce-recomp -package base -fplugin=LiquidHaskell   tests/pos/GCD.hs 
Loaded package environment from /home/waldmann/.ghc/x86_64-linux-9.8.1/environments/default
[1 of 1] Compiling GCD              ( tests/pos/GCD.hs, tests/pos/GCD.o )

tests/pos/GCD.hs:5:14: error:
    Unknown type constructor `Nat`
    matchTyCon: Nat
  |
5 | {-@ mod :: a:Nat -> b:{v:Nat| ((v < a) && (v > 0))} -> {v:Nat | v < b} @-}
  |              ^^^

[jwaldmann]

works via stack:

$ PATH=/opt/ghc/ghc-9.8.1/bin:$PATH stack exec -- ghc -fforce-recomp -fplugin=LiquidHaskell tests/pos/GCD.hs

Warning: Stack has not been tested with GHC versions 9.8 and above, and using 9.8.1, this may fail.
[1 of 1] Compiling GCD              ( tests/pos/GCD.hs, tests/pos/GCD.o )

**** LIQUID: SAFE (32 constraints checked) *************************************