v0.6.0

• Allow range parsers to have an open upper or lower bound. For example 0.. is a parser for integers greater than or equal to zero.
• Range parsers may be used in patterns. For example int -> 0.. fails if the parsed integer is not greater than or equal to zero.
• Add meta function @Crash(Message) to immediately halt the program with a custom error message.
• Add stdlib parsers repeat(p, N), repeat_between(p, N, M), tuple(elem, N), and tuple_sep(elem, sep, N) for repeating a parser a fixed number of times.

In addition to enabling the new standard library parsers, with range patterns we can write a naive nth-digit Fibonacci function as a suitably feral one-liner

$ possum -p '0.. -> N $ Fib(N) ; Fib(N) = N -> ..1 | (Fib(N - 1) + Fib(N - 2))' -i 11
89

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