[−][src]Crate monadic
Haskell style block macros "mdo" where monad sources should be expressions of type instances of IntoIterator.
Each monad expression is flat_mapped (into_iter().flat_map( lambda)
)
with the lambda expression having the monad result variable as argument and the rest as its body,
into a lazy FlatMap expression that is also an instance of IntoIterator, and can be collected into any instance of FromIterator.
To use "mdo" (module monad
) you must import the traits Bind and Monad defined there.
There are transitive implementation relations for some structures to be instances of IntoIterator:
All iterators implement IntoIterator where into_iter() returns the self iterator structure as documented
Iterator and IntoIterator trait imports are predefined
There are also Reader, Writer and State monads in their respective modules with their own macros.
use num::Integer; use monadic::{mdo, monad::{Bind, Monad}}; // available in examples/comprehension.rs let xs = mdo!{ x <- 1..7; y <- 1..x; guard (&y).is_odd() ; let z = match x.is_even() { true => &y + 1, _ => &y - 1, }; pure (x, z) }.collect::<Vec<(i32,i32)>>(); println!("result: {:?}", xs); // now with container and item references, available in examples/comprehension2.rs let ys = mdo!{ &x <- &vec![1,2,3,4]; // with item refs (&x) in the lambda argument position guard x.is_odd() ; let z = x + 1 ; pure (x, z) }.collect::<Vec<(i32,i32)>>(); println!("result: {:?}", ys);
Modules
mio | |
monad | definition of Bind and Monad traits based monadic macro |
monoid | Semigroup and Monoid to use with Writer |
reader | |
reader_trans | |
state | A State monad implementation |
state_trans | |
util | |
writer | A Writer monad implementation |
writer_trans |
Macros
mdo | macro for iterables (IntoIterator) as monads enabling monad comprehensions over iterables |
rdrdo | macro for a |
rdrt_mdo | macro for a |
stdo | macro for a |
stt_mdo | macro for a |
wrdo | macro for a |
wrt_mdo | macro for a |