Document why all functions return `Maybe String` rather than `String`

[jameshfisher]

Why do all the Haskeline functions return a Maybe String rather than a String? There's no documentation on it, and it seems to me that they should always return String, like standard getLine. I have no idea what the interpretation of Nothing is.

[judah]

The documentation is at the start of the section titled "User interaction functions": http://hackage.haskell.org/package/haskeline-0.7.1.1/docs/System-Console-Haskeline.html#g:4

Probably it could be changed to make the reference to Nothing more prominent. For example:

The following functions read one line or character of input from the user.

They return Nothing if they encounter the end of input:
- When using terminal-style interaction, if the user pressed Ctrl-D when the input text was empty.
- When using file-style interaction, if an EOF was encountered before any characters were read.

Do you think that would be more clear?

[jameshfisher]

Ahhh. Yes, that looks clear to me! J. On Dec 24, 2013 8:10 PM, "Judah Jacobson" notifications@github.com wrote:

The documentation is at the start of the section titled "User interaction functions":

http://hackage.haskell.org/package/haskeline-0.7.1.1/docs/System-Console-Haskeline.html#g:4

Probably it could be changed to make the reference to Nothing more prominent. For example:

The following functions read one line or character of input from the user.

They return Nothing if they encounter the end of input:

• When using terminal-style interaction, if the user pressed Ctrl-D when the input text was empty.
• When using file-style interaction, if an EOF was encountered before any characters were read.

Do you think that would be more clear?

— Reply to this email directly or view it on GitHubhttps://github.com/judah/haskeline/issues/3#issuecomment-31183822 .