On Sat, Jan 09, 2016 at 06:29:05PM +0100, Jerzy Karczmarczuk wrote:
Tom Ellis wrote :
consider a lazy language, Haskell--,/which doesn't allow recursive bindings of non-function types./ In Haskell-- you *cannot* write
exps = 1 + integral exps
but you have to write
exps = I.fix (\e -> 1 + integral e)
So we see that the nice syntax "exps = 1 + integral exps" is not due to laziness (since Haskell-- is lazy, but you cannot write that).
Tom, construct such a language, and I might believe you.
By the way, for explicitness, here is my construction of such a language. Take any strict language and extend the rules for let rec such that let rec v = ... v ... means let v = fix (\v' -> ... v' ...) for any v that has lazy type (function types, explicit thunks etc.), where fix is its associated fixpoint operator. Then one can happily write let rec exps = 1 + integral exps because it means exactly Oleg's let exps = fix (\e -> 1 + integral e) Do you say (a) this language can't exist for some reason or (b) it is somehow "not strict"? Tom