Exercise 3.

Consider the following syntax-directed definition.

Production	Semantic Rule
S $\longmapsto$ E	E.env := initialEnv()
E1 $\longmapsto$ $\bf let$ $\bf id$ $\bf =$ E2 $\bf in$ E3 $\bf end$	E2.env := E1.env
	E3.env := Update( E1.env,$\bf id$, E2.val)
	E1.val := E3.val
E1 $\longmapsto$ (E2 + E3)	E1.val := E2.val + E3.val
	E2.env := E1.env
	E3.env := E1.env
E $\longmapsto$ $\bf id$	E.val := LookUp( $\bf id$, E.env)
E $\longmapsto$ $\bf 1$	E.val := $\bf 1$
E $\longmapsto$ $\bf0$	E.val := $\bf0$

Write a translation scheme for this syntax-directed definition.

Answer 3  

S	$\longmapsto$
E1	$\longmapsto$
E1	$\longmapsto$
E	$\longmapsto$
E	$\longmapsto$
E	$\longmapsto$