Direction of data flow

In Haskell the direction of data flow symbolized by the notations differs amongst the notations. Both directions occur equally frequently:

from left to right:

function definition	f x = x*x	(input left, output right)
Lambda	\ x -> x*x
do notation	do f; g
monadic composition	f >>= g
let expression	let x = 2 in x*x	(first definition, then usage)

from right to left:

function application	f x, f $ x	(input right, applied function left)
composition	g . f
results of monads	do x <- f
monadic composition	g =<< f
where clause	x*x where x = 2	(first usage, then definition)

Weblinks

• http://www.haskell.org/pipermail/libraries/2005-August/004315.html
• http://www.iba-cg.de/doc/hal1-haskell-with-style.pdf

See also

There is still something to translate from De/Flussrichtung