Succinct FSharp

Page walks through F# through examples and explanations, starting with F# Interactive and basic evaluation in fsi. It then covers immutable bindings, let, mutable values, whitespace sensitivity, primitive types, strings, tuples, collections, slices, comments, conditionals, loops, functions, currying, pipelines, recursion, and pattern matching.

Reading notes

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• fsi is presented as a practical way to learn F#, started with dotnet fsi and controlled with #help;;, #quit;;, and ;; to end input.
• Expression results are stored in it, which has a type, and it is not mutable.
• let creates bindings, let mutable creates variables that can be updated with <-, and = is used for comparison.
• let..in is shown as equivalent to let, and lambda functions are introduced through that equivalence.
• Double-backtick identifiers allow names with spaces and symbols.
• F# is whitespace sensitive and uses indentation instead of braces.
• Primitive types listed include bool, byte, int, float, double, float32, single, char, string, and unit.
• Strings can be concatenated, written as verbatim strings with @, written as multiline strings with triple quotes, or interpolated with $.
• Tuples can hold values of different types, be deconstructed, and be accessed with fst and snd.
• Lists are immutable, arrays are fixed-size and mutable, sequences are lazy, and slices work on lists, arrays, and 2-D arrays.
• Comments can be block, line, or XML doc comments.
• if..then..else, for..in, for..to, and while..do are presented as expressions.
• Functions are defined with let, can have explicit types, can be anonymous, can capture outer bindings, and can be curried.
• Pipe |> and composition >> are shown for chaining functions.
• Recursive functions use rec, and mutual recursion uses and.
• Pattern matching uses match, with _ as wildcard and when as a guard.
• function is presented as shorthand for fun x -> match x with.
• Cons patterns, active patterns, parameterized active patterns, and partial active patterns are included.
• Records, anonymous records, discriminated unions, option, and Result are covered as data modeling tools.
• Generic type inference and automatic generalization are shown with generic list functions.
• Exceptions are handled with failwith, try/with, custom exceptions, and try/finally.
• Classes, inheritance, interfaces, object expressions, and compiler directives such as #load, #r, #I, and #if INTERACTIVE close the page.