haskell.day :: A Pure Day in Four Evaluations
day ::IOProofhaskell.day

01 / Morning Lambda

A small lambda begins the light.

Pure functions cast measured shadows. A value enters as x, waits in theorem-space, then turns toward dawn.

λx . x
identity :: a -> a

02 / Noon Composition

Composition makes noon from smaller mornings.

Layered panes receive a value, refract it through functions, and return a brighter expression without breaking purity.

-> . ->
Functor => Applicative => Monad

03 / Evening Laziness

A value waits until observed.

The infinite list is not a road but a promise: dusk writes only the cells that attention demands.

where stream = 1 : map (+1) stream
.

04 / Midnight Monad

The whole day folds into bind.

Gold sparks quiet down. Violet glass becomes ink. The final expression is not an ending, but a lawful way to continue.

>>= =
“A quiet proof, evaluated by the shape of the day.”