Re: [Haskell-cafe] Substituting values

Yeah, I guess I was wondering whether something like it already existed. Thinking about it some more, perhaps what I want is `tr` [1]. E.g. tr [Foo] [Bar] Incorporating your suggestion would then yield a more general version like: trBy (== Foo) Bar [1] http://en.wikipedia.org/wiki/Tr_(Unix) On Sat, Dec 22, 2012 at 6:46 AM, David Thomas wrote:

Seems like the function is easy to define:

replaceIfEq a b c = if c == a then b else c

Then the above can be written

replaceIfEq Foo Bar value

Or the slightly more general (in exchange for slightly more verbosity at the call site)

replaceIf p r a = if p a then r else a

replaceIf (== Foo) Bar value

On Fri, Dec 21, 2012 at 6:46 PM, Radical wrote:

...

Sometimes I'll need something like:

if value == Foo then Bar else value

Or some syntactic variation thereof:

case value of { Foo -> Bar; _ -> value }

Is there a better/shorter way to do it? I'm surprised that it's more complicated to substitute a value on its own than e.g. in a list, using filter. Or perhaps I'm missing the right abstraction?

Thanks,

Alvaro

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