Variant structure

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The Variant structure provides operations for working with the variant type, which can hold values of any type in a dynamically-typed fashion.

Synopsis

datatype variant
  = UNIT
  | BOOL of bool
  | INT of int
  | REAL of real
  | CHAR of char
  | STRING of string
  | LIST of variant list
  | BAG of variant list
  | VECTOR of variant list
  | VARIANT_NONE
  | VARIANT_SOME of variant
  | RECORD of (string * variant) list
  | CONSTANT of string
  | CONSTRUCT of string * variant

val parse : string -> variant
val print : variant -> string

datatype variant

is a dynamically-typed value that can hold any Morel value.

parse

parse s parses a variant from its string representation.

The string is in the format produced by the print function, and therefore parse (print v) = v for all variant values v.

print

print v (or v.print ()) converts a variant to a string.

For example, print (BOOL true) returns "BOOL true"; print (LIST [INT 1, INT 2]) returns "LIST [INT 1, INT 2]".