Can I tell GHC to just typecheck my code without actually compiling it?

Question

I'm prototyping and messing around with the types in my program and I currently use ghc --make whenever I want to do a type check. However, this command also spends time to compile and link a real executable that I don't need just yet. Is there some flag I can pass to ghc to tell it to do just the typechecking?

I just added a caveat to the answer that was given to me: in-exhaustive patterns are not checked. — Christopher Done, Jul 30 '13 at 08:07

score 13 · Answer 1 · edited Jul 30 '13 at 08:30

13

Passing the -fno-code flag to ghc will do what you need.

$ ghc -fno-code myfile.hs

edited Jul 30 '13 at 08:30

Chris Taylor

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answered Jul 30 '13 at 07:49

Mark Wotton

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score 3 · Answer 2 · answered Jul 30 '13 at 06:44

GHCi will type-check your code and compile it, but will generally be much faster than GHC even with -O0. If that's not sufficient, there are also programs like hdevtools and ghc-mod that exist for this purpose -- they're generally meant to be integrated with a text editor but can also be used standalone.

(Another option that might speed things up a bit with just the regular compiler is -S, which stops after generating assembly without assembling or linking.)

Can I tell GHC to just typecheck my code without actually compiling it?

2 Answers2