Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The FSI file type is primarily associated with 'F#' by Microsoft Corporation.
F# (pronounced F Sharp) is a scalable, succinct, type-safe, type-inferred, efficiently executing functional/imperative/object-oriented programming language.
It aims to be the premier type-safe functional programming language for the .NET framework and other implementations of the Ecma 335 Common Language Infrastructure specification.
F# was partially inspired by the OCaml language and shares some common core constructs with it.
The inputs to the F# compiler or the F# Interactive dynamic compiler consist of source code files, with extensions .fs, .fsi, .ml, .mli, .fsx, .fsscript.
- Files with extension .fs, .ml must conform to grammar element implementation-file.
- Files with extension .fsi, .mli must conform to grammar element signature-file.
- Files with extension .fsx and .fsscript are processed just as for those with extension .fs except that the conditional compilation symbol INTERACTIVE is defined instead of COMPILED, the assembly FSharp.Compiler.Interactive.Settings.dll is referenced by default, and the namespace Microsoft.FSharp.Compiler.Interactive.Settings is opened by default.