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This package defines julia implementations for the common types Option (aka Maybe), Either and Try, as well as one extra type ContextManager which mimics Python's with-ContextManager.


Here an example using Try to handle errors programmatically. Similar to Option, a Try is either a Const, denoting an error, or an Identity value, which denotes success.

using DataTypesBasic  # defines Try

@Try div(1, 0)  # Const(Thrown(DivideError()))
@Try div(8, 3)  # Identity(2)

Using another helper package Monadic. We can combine these into nice syntax.

using Monadic  # defines @monadic

# flatmap is also defined in TypeClasses.jl
flatmap(f, x) = Iterators.flatten(map(f, x))
tryit = @monadic map flatmap begin
  a = @Try div(8, 3)
  b = @Try isodd(a) ? 100 + a : error("fail")
  @pure a, b
# Const(Thrown(ErrorException("fail")))

For more details check out the documentation.