Injective types. This module contains the Injective typeclass and instances for the following equivalence classes:

• {Strict Text, Lazy Text, String}. ByteStrings are not part of this, since there is more than one way to turn unicode text into a ByteString (see Data.Text.Encoding and Data.Text.Lazy.Encoding).
• {Whole, Integer}. Be advised, though, that Peano numbers may contain unobservable infinities (i.e. infinity = S infinity) and thus, the conversion to Integer may not terminate.
• {Nat, Natural}. For finite values, they're extensionally equivalent, but Nat has lazy infinity.
• {Seq a, Vector a}. Supports all kinds of immutable vectors of elements: boxed, unboxed, primitive, storable. [a] is not part of this, as typeclass IsList provides fromList and toList.

Additional injections:

• Maybe to Either (the reverse is not true, since different Left values would all be converted to Nothing).
• Integers to Rational.
• Natural numbers to Integer and Rational.