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Parametrized active patterns
f#

I defined the active pattern "Expression" as follows:

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let (|Expression|_|) expression _ = Some(expression)

Now I'm trying to use it in this way:

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match () with

| Expression((totalWidth - wLeft - wRight) / (float model.Columns.Count - 0.5)) cw

    when cw <= wLeft * 4. && cw <= wRight * 4. ->

        cw

| Expression((totalWidth - wLeft) / (float model.Columns.Count - .25)) cw

    when cw <= wLeft * 4. && cw > wRight * 4. ->

        cw

| Expression((totalWidth - wRight) / (float model.Columns.Count - .25)) cw

    when cw > wLeft * 4. && cw <= wRight * 4. ->

        cw

| Expression(totalWidth / float model.Columns.Count) cw

    when cw > wLeft * 4. && cw > wRight * 4. ->

        cw

| _ -> System.InvalidProgramException() |> raise

But this results in "error FS0010: Unexpected symbol '-' in pattern". Is that fixable?

What am I trying to do is to write clearly a solution to the following equation:
max(wl - cw * .25, 0) + max(wr - cw * .25) + cw * columnCount = ActualWidth

where cw is the only variable.

Can you suggest any better way?

.

Why not just follow the equation to get actualWidth instead?

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let actualWidth wl wr colCot cw = (max(wl - cw * 0.25) 0.0) + (max(wr - cw * 0.25) 0.0) + cw * colCot
By on 5/30/2011 2:09 PM ()

I need to solve it for cw. Did you read the head post carefully?

By on 6/1/2011 6:24 AM ()

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