Hello there:
I have a small piece of code which I don't know where is the problem.
===================================================
let str_IND, str_RECUR = define_type "str = Str (int list)";;
let expr_IND, expr_RECUR = define_type
" expr = Lit num
|Var str
|Plus expr expr
|Times expr expr ";;
let cmd_IND, cmd_REC = define_type
"cmd = Assign str expr
| Seq cmd cmd
| If expr cmd cmd
| While expr cmd";;
parse_as_infix(";;", (18, "right"));;
parse_as_infix(":=", (20, "right"));;
override_interface(";;", `Seq`);;
override_interface(":= ", `Assign`);;
override_interface("+", `Plus`);;
override_interface("*", `Times`);;
let value = define
`(value (Lit n ) s = n )
/\ (value (Var x) s = s(x) )
/\ (value (e + f) s = value e s + value f s )
/\ (value (e * f) s = value e s * value f s ) `;;
=======================================
Exception: Failure "typechecking error (initial type assignment)".
after that , the system seemed enter an unstable state:
# let fib = define
`fib n = if n = 0 \/ n = 1 then 1 else fib(n-1) + fib(n-2)`;;
Exception: Failure "typechecking error (initial type assignment)".
any help ?
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