Pattern matching on each-of types (bad vs good style) ML

	fun sum_triple_bad_style triple =
	case triple of (x,y,z) => x + y + z
	fun sum_triple_better_style triple =
	let val (x,y,z) = triple
	in
	x + y + z
	end
	fun sum_triple_best_style (x,y,z) = x + y + z
	(*
	assume a record looks like
	{ first="Robby", last="Pelssers"}
	*)
	fun full_name_bad_style r =
	case r of {first=f, last=l} => f ^ " " ^ l
	fun full_name_better_style r =
	let val {first=f, last=l} = r
	in
	f ^ " " ^ l
	end
	fun full_name_best_style {first=f, last=l} = f ^ " " ^ l
	val sum1 = sum_triple_bad_style (1,2,3)
	val sum2 = sum_triple_better_style (1,2,3)
	val sum3 = sum_triple_best_style (1,2,3)
	val fullname1 = full_name_bad_style({first="Robby", last="Pelssers"})
	val fullname2 = full_name_better_style({first="Robby", last="Pelssers"})
	val fullname3 = full_name_best_style({first="Robby", last="Pelssers"})
	(* output of program
	- use "patterns.sml";
	[opening patterns.sml]
	val sum_triple_bad_style = fn : int * int * int -> int
	val sum_triple_better_style = fn : int * int * int -> int
	val sum_triple_best_style = fn : int * int * int -> int
	val full_name_bad_style = fn : {first:string, last:string} -> string
	val full_name_better_style = fn : {first:string, last:string} -> string
	val full_name_best_style = fn : {first:string, last:string} -> string
	val sum1 = 6 : int
	val sum2 = 6 : int
	val sum3 = 6 : int
	val fullname1 = "Robby Pelssers" : string
	val fullname2 = "Robby Pelssers" : string
	val fullname3 = "Robby Pelssers" : string
	val it = () : unit
	*)

view raw gistfile1.sml hosted with ❤ by GitHub