GHCi: Behave nicely on `-e`, like `ghc` and other programs (#9360) · Issues · Glasgow Haskell Compiler / GHC

GHCi: Behave nicely on `-e`, like `ghc` and other programs

Like many programming language environments, GHC offers a handy -e option for evaluating an expression, then returning to the shell.

$ ghc -e '2 + 2'

4

One would expect the interpreter, GHCi, to offer a similar flag, but it surprisingly rejects it.

ghci -e '2 + 2'

ghc: on the commandline: cannot use `--interactive' with `-e'

Usage: For basic information, try the `--help' option.

I think this behavior is quite unintuitive--when I pass -e <exp> to ghci, or pass --interactive -e <exp> to ghc, I expect the expression to be evaluated as the leading expression in an interactive interpreter session.

Could we please tweak ghc like this to make it slightly more intuitive when these flags are used together?

Trac metadata

Trac field	Value
Version	7.8.2
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

Like many programming language environments, GHC offers a handy `-e` option for evaluating an expression, then returning to the shell.

```
$ ghc -e '2 + 2'

4
```

One would expect the interpreter, GHCi, to offer a similar flag, but it surprisingly rejects it.

```
ghci -e '2 + 2'

ghc: on the commandline: cannot use `--interactive' with `-e'

Usage: For basic information, try the `--help' option.
```

I think this behavior is quite unintuitive--when I pass `-e <exp>` to ghci, or pass `--interactive -e <exp>` to ghc, I expect the expression to be evaluated as the leading expression in an interactive interpreter session.

Could we please tweak ghc like this to make it slightly more intuitive when these flags are used together?

<details><summary>Trac metadata</summary>

| Trac field             | Value          |
| ---------------------- | -------------- |
| Version                | 7.8.2          |
| Type                   | FeatureRequest |
| TypeOfFailure          | OtherFailure   |
| Priority               | normal         |
| Resolution             | Unresolved     |
| Component              | Compiler       |
| Test case              |                |
| Differential revisions |                |
| BlockedBy              |                |
| Related                |                |
| Blocking               |                |
| CC                     |                |
| Operating system       |                |
| Architecture           |                |

</details>