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I didn't know what "point-free style programming" was so: > Tacit programming (point-free programming) is a programming paradigm in which a function definition

by baby 4y ago

I didn't know what "point-free style programming" was so: > Tacit programming (point-free programming) is a programming paradigm in which a function definition does not include information regarding its arguments, using combinators and function composition [...] instead of variables. from https://stackoverflow.com/questions/944446/what-is-point-free-style-in-functional-programming https://stackoverflow.com/questions/944446/what-is-point-fre... I guess it's the fact that in programming languages like OCaml you write functions like that: let some_fn arg1 arg2 = ... and so you can partially apply them: * using `some_fn` without any argument is manipulating a function with two arguments * using `some_fn arg1` returns a new function that only takes one argument * using `some_fn arg1 arg2` applies the entire function

omegaham 4y ago
Note that in OCaml, you can't get too screwy with point-free programming because of the value restriction. It is possible to compose functions in a point-free manner, but those functions themselves have to have points if you want them to be generic. Standard example: let last xs = List.fold_left (fun x y -> Some y) None xs This is of type last : 'a list -> 'a option = <fun> Neat, `'a` is generic. Let's η-reduce out the `xs` and make the function point-free (ignoring the lambda): let last = List.fold_left (fun x y -> Some y) None This doesn't work the way that we want: last : '_weak1 list -> '_weak1 option = <fun> The moment that we call this weakly polymorphic function, its type is fixed and is no longer generic. In the toplevel: # last [1;2;3];; - : int option = Some 3 # last['x';'y';'z'];; Error: This expression has type char but an expression was expected of type int Haskell, of course, is totally happy to let you do point-free mania with Kleisli arrows and all of the rest of it.

by baby 4y ago

omegaham 4y ago

Note that in OCaml, you can't get too screwy with point-free programming because of the value restriction. It is possible to compose functions in a point-free manner, but those functions themselves have to have points if you want them to be generic. Standard example: let last xs = List.fold_left (fun x y -> Some y) None xs This is of type last : 'a list -> 'a option = <fun> Neat, `'a` is generic. Let's η-reduce out the `xs` and make the function point-free (ignoring the lambda): let last = List.fold_left (fun x y -> Some y) None This doesn't work the way that we want: last : '_weak1 list -> '_weak1 option = <fun> The moment that we call this weakly polymorphic function, its type is fixed and is no longer generic. In the toplevel: # last [1;2;3];; - : int option = Some 3 # last['x';'y';'z'];; Error: This expression has type char but an expression was expected of type int Haskell, of course, is totally happy to let you do point-free mania with Kleisli arrows and all of the rest of it.