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Re: ``Update functions'' in Scheme.
SETL, the set language, used such left-hand-side ("sinister") update
functions and made them compose correctly. Unfortunately, I no longer have
a SETL manual available.
As I recall, evaluating nested updates can involve two calls to functions,
one in a dexter context and one in a sinister context.
F(G(A)) <- B
should ensure that, after assignment,
F(G(A)) = B
It seems like you need
T1 <- G(A) G dexter
F(T1) <- B F sinister
G(A) <- T1 G sinister
F(G(A)) = F(T1) = B
As for about F(G(A),H(B)) <- C
T1 <- G(A), T2 <- H(B)
F(T1,T2) <- C
G(A) <- T1,H(B) <- T2
Anyone know SETL? Jeff?