General Computer Science 320201 GenCS I & II Lecture ... - Kwarc

let
fun exp(x,n) =
if n i
| _ => raise Error("Argument expected: " \^ i)
fun lookupP (i,env) =
case lookup(i,env) of
Proc ca => ca
| _ => raise Error("Procedure expected: " \^ i)
c○: Michael Kohlhase 320
Next we define a function that compiles abstract µML expressions into lists of abstract L(VMP)
instructions. As expressions also appear in argument sequences, it is convenient to define a function
that compiles µML expression lists via left folding. Note that the two expression compilers are
very naturally mutually recursive. Another trick we already do is that we give the expression
compiler an argument tail, which can be used to append a list of L(VMP) commands to the result;
this will be useful in the declaration compiler later to take care of the return statment needed to
return from recursive functions.
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