[Haskell-cafe] Monad of no `return` Proposal

Richard A. O'Keefe ok at cs.otago.ac.nz
Fri Oct 9 03:18:19 UTC 2015


On 6/10/2015, at 10:16 pm, Kosyrev Serge <_deepfire at feelingofgreen.ru> wrote:
> As an example of the opposite end, consider Common Lisp, which:
> 
>  1. reifies READ as the third processing phase (macroexpansion[1] and actual
>     compilation being the other two)
>  2. operates at expression granularity
>  3. makes the full power of the language available to support the
>     decision process of what subexpressions are available in which
>     contexts

Except that the syntax for conditional reading in Common Lisp,
    #+ <feature> <datum>
    #- <feature> <datum>
(a) is utterly different from conditional evaluation,
    like (if <expr> <expr> <expr>).
(b) does NOT make the full power of the language available.
    The feature test is a Boolean combination, using and, or, not
    of atoms, where the value of an atom is true iff it is a
    member of *features* (the asterisks are part of the name).




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