Add generic print and println functions to FSharp.Core #19265
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Add `print: 'T -> unit` and `println: 'T -> unit` to ExtraTopLevelOperators. These use the existing `string` function for conversion (InvariantCulture for IFormattable, .ToString() fallback) and write to Console.Out.
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❗ Release notes required
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vzarytovskii
reviewed
Feb 9, 2026
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| [<CompiledName("PrintValue")>] | ||
| let print (value: 'T) = | ||
| Console.Out.Write(string value) | ||
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| [<CompiledName("PrintValueLine")>] | ||
| let println (value: 'T) = | ||
| Console.Out.WriteLine(string value) | ||
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Should functions be inline?
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Summary
This is another take on RFC FS-1125, following up on the closed #13597. I guess that's mostly an attempt to see if anyone's interested in driving the old proposal to the finish line. For me those would definitely be handy functions to have, but obviously they are not something very important.
The key difference from the original PR is that
printandprintlnare generic ('T -> unit) rather thanstring -> unit, addressing the feedback from @dsyme that a generic print function would be a better use of the "good name":Both functions use the existing
stringoperator for conversion, which already:IFormattabletypes (consistent withprintfn,sprintf, etc.).ToString()for other types (F# types likeOption,List, etc. have good.ToString()overrides)Changes
printandprintlnsignatures with XML docs tofslib-extra-pervasives.fsifslib-extra-pervasives.fsPrintTests.fs) covering: string, int, float, bool, Option, None, list, newline behavior, and concatenationOpen questions
eprintf(n)andfprintf(n)? Do they generic counterparts as well?