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POHow do you declare the values of a dictionary entry as mutable?
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  1. POHow do you declare the values of a dictionary entry as mutable?
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    copied!<p>The Google yields plenty of example of adding and deleting entries in an F# dictionary (or other collection). But I don't see examples to the equivalent of</p> <pre><code>myDict["Key"] = MyValue; </code></pre> <p>I've tried</p> <pre><code>myDict.["Key"] &lt;- MyValue </code></pre> <p>I have also attempted to declare the Dictionary as</p> <pre><code>Dictionary&lt;string, mutable string&gt; </code></pre> <p>as well several variants on this. However, I haven't hit on the correct combination yet... if it <em>is</em> actually possible in F#.</p> <p>Edit: The offending code is:</p> <pre><code>type Config(?fileName : string) = let fileName = defaultArg fileName @"C:\path\myConfigs.ini" static let settings = dict[ "Setting1", "1"; "Setting2", "2"; "Debug", "0"; "State", "Disarray";] let settingRegex = new Regex(@"\s*(?&lt;key&gt;([^;#=]*[^;#= ]))\s*=\s*(?&lt;value&gt;([^;#]*[^;# ]))") do File.ReadAllLines(fileName) |&gt; Seq.map(fun line -&gt; settingRegex.Match(line)) |&gt; Seq.filter(fun mtch -&gt; mtch.Success) |&gt; Seq.iter(fun mtch -&gt; settings.[mtch.Groups.Item("key").Value] &lt;- mtch.Groups.Item("value").Value) </code></pre> <p>The error I'm getting is:</p> <pre><code>System.NotSupportedException: This value may not be mutated at Microsoft.FSharp.Core.ExtraTopLevelOperators.dict@37-2.set_Item(K key, V value) at &lt;StartupCode$FSI_0036&gt;.$FSI_0036_Config.$ctor@25-6.Invoke(Match mtch) at Microsoft.FSharp.Collections.SeqModule.iter[T](FastFunc`2 action, IEnumerable`1 sequence) at FSI_0036.Utilities.Config..ctor(Option`1 fileName) at &lt;StartupCode$FSI_0041&gt;.$FSI_0041.main@() stopped due to error </code></pre>
 

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