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Re: [Haskell-beginners] import not...

Galaxy Being

4 Jun 2021 4 Jun '21

5:48 p.m.

I go to a directory. I run stack install Safe I start up ghci and get the Prelude prompt. I run import Safe and I get import Safe | ^^^^^^^^^^^ Failed, no modules loaded. I'm once again frustrated. I try to load this hs file {-# LANGUAGE ViewPatterns #-} {-# LANGUAGE NoMonomorphismRestriction #-} import Safe lookupDefault :: Eq a => a -> b -> [(a,b)] -> b lookupDefault k _ (lookup k -> Just s) = s lookupDefault _ d _ = d headTup :: (a, [t]) -> [t] headTup (headMay . snd -> Just n) = [n] headTup _ = [] headNil :: [a] -> [a] headNil (headMay -> Just x) = [x] headNil _ = [] with the same result. What do I need to do? -- ⨽ Lawrence Bottorff Grand Marais, MN, USA borgauf@gmail.com

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Jesse Rudel

4 Jun 4 Jun

6:18 p.m.

How are you invoking ghci? If it's a stack project you can try stack ghci if you haven't already. On Fri, 4 Jun 2021 at 21:51, Galaxy Being wrote:

...

I go to a directory. I run

stack install Safe

I start up ghci and get the Prelude prompt. I run

import Safe

and I get

import Safe | ^^^^^^^^^^^ Failed, no modules loaded.

I'm once again frustrated. I try to load this hs file

{-# LANGUAGE ViewPatterns #-} {-# LANGUAGE NoMonomorphismRestriction #-}

import Safe

lookupDefault :: Eq a => a -> b -> [(a,b)] -> b lookupDefault k _ (lookup k -> Just s) = s lookupDefault _ d _ = d

headTup :: (a, [t]) -> [t] headTup (headMay . snd -> Just n) = [n] headTup _ = []

headNil :: [a] -> [a] headNil (headMay -> Just x) = [x] headNil _ = []

with the same result. What do I need to do? -- ⨽ Lawrence Bottorff Grand Marais, MN, USA borgauf@gmail.com _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

Galaxy Being

11:47 p.m.

I run ghci with

...

stack ghci

On Fri, Jun 4, 2021 at 5:19 PM Jesse Rudel wrote:

...

How are you invoking ghci? If it's a stack project you can try stack ghci if you haven't already.

On Fri, 4 Jun 2021 at 21:51, Galaxy Being wrote:

...
I go to a directory. I run

stack install Safe

I start up ghci and get the Prelude prompt. I run

import Safe

and I get

import Safe | ^^^^^^^^^^^ Failed, no modules loaded.

I'm once again frustrated. I try to load this hs file

{-# LANGUAGE ViewPatterns #-} {-# LANGUAGE NoMonomorphismRestriction #-}

import Safe

lookupDefault :: Eq a => a -> b -> [(a,b)] -> b lookupDefault k _ (lookup k -> Just s) = s lookupDefault _ d _ = d

headTup :: (a, [t]) -> [t] headTup (headMay . snd -> Just n) = [n] headTup _ = []

headNil :: [a] -> [a] headNil (headMay -> Just x) = [x] headNil _ = []

with the same result. What do I need to do? -- ⨽ Lawrence Bottorff Grand Marais, MN, USA borgauf@gmail.com _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

_______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

-- ⨽ Lawrence Bottorff Grand Marais, MN, USA borgauf@gmail.com

Galaxy Being

5 Jun 5 Jun

6:23 p.m.

Let me reiterate, I'm not creating a stack project formally. I'm just going to some directory at the command prompt and firing up ghci, which I presume just uses the global installs. Then I'm creating .hs files in a text editor and trying to load them at the REPL. How can I install stuff in this instance? On Fri, Jun 4, 2021 at 10:47 PM Galaxy Being wrote:

...

I run ghci with

...
stack ghci

On Fri, Jun 4, 2021 at 5:19 PM Jesse Rudel wrote:

...
How are you invoking ghci? If it's a stack project you can try stack ghci if you haven't already.

On Fri, 4 Jun 2021 at 21:51, Galaxy Being wrote:

...
I go to a directory. I run

stack install Safe

I start up ghci and get the Prelude prompt. I run

import Safe

and I get

import Safe | ^^^^^^^^^^^ Failed, no modules loaded.

I'm once again frustrated. I try to load this hs file

{-# LANGUAGE ViewPatterns #-} {-# LANGUAGE NoMonomorphismRestriction #-}

import Safe

lookupDefault :: Eq a => a -> b -> [(a,b)] -> b lookupDefault k _ (lookup k -> Just s) = s lookupDefault _ d _ = d

headTup :: (a, [t]) -> [t] headTup (headMay . snd -> Just n) = [n] headTup _ = []

headNil :: [a] -> [a] headNil (headMay -> Just x) = [x] headNil _ = []

with the same result. What do I need to do? -- ⨽ Lawrence Bottorff Grand Marais, MN, USA borgauf@gmail.com _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

_______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

-- ⨽ Lawrence Bottorff Grand Marais, MN, USA borgauf@gmail.com

-- ⨽ Lawrence Bottorff Grand Marais, MN, USA borgauf@gmail.com

Travis Cardwell

8:32 p.m.

The `stack ghci` command does not load extra packages such as those installed "globally." This is a good thing, IMHO. You can instruct the command to load specific packages using the `--package` option. Example: stack repl --package safe Example using your file: stack repl --package safe GalaxyBeing.hs Note that your email indicates usage of the `Safe` package (uppercase), but that package is deprecated in favor of the `safe` package (lowercase). I mention it in case it is not intentional. * https://hackage.haskell.org/package/safe * https://hackage.haskell.org/package/Safe You may want to create a project that is just for testing. You can then specify which Stack snapshot to use in `stack.yaml` and which packages to use in `package.yaml`. stack new experiment Travis

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Galaxy Being
Jesse Rudel
Travis Cardwell