The language defined in Sect. 4.2 declares types of parameters and results of functions. The interpreter in Sect. 4.3 adds explicit type information to every value, and checks this before doing any...

The language defined in Sect. 4.2 declares types of parameters and

results of functions. The interpreter in Sect. 4.3 adds explicit type information to

every value, and checks this before doing any operations on values. So, we could

omit type declarations and rely solely on the type information in values.

Replace in Grammar 4.1 TypeId by id and rewrite the interpretation functions

in Fig. 4.3 so they omit checking types of parameters and results, but still check

that the number of arguments match the declaration and that no parameter name is

repeated.