# [plt-scheme] writing an evaluation function/interpreter; type-case

Hi,
I'm trying to follow Ch. 4 of Types and Programming Languages by
Benjamin Pierce and implement the language
t:= true | false | if t then t else t
OR using define-type
(define-type term
[TmTrue (t (lambda (a) (equal? a #t)))]
[TmFalse (f (lambda (a) (equal? a #f)))]
[TmIf (t1 term?) (t2 term?) (t3 term?)])
I was trying to use the forms define-type and type-case from PLAI by
Shriram Krishnamurthi, but type-case doesn't seem to have the same
pattern matching functionality as is used Pierce's ocaml
implementation i.e. I can't write
(define (eval1 e)
(type-case term e
[TmTrue (t) t]
[TmFalse(f) f]
[TmIf (TmTrue t2 t3) (eval1 t2)]
[TmIf (TmFalse t2 t3) (eval1 t3)]))
I was trying to use "match", but it doesn't seem to be defined to work
with the algebraic data type defined with define-type (or perhaps I am
using match incorrectly).
(define (eval1 e)
(type-case term e
[TmTrue (t) t]
[TmFalse(f) f]
[TmIf (t1 t2 t3) (match t1)
]
Can anyone give guidance on the proper way to implement this in
scheme? Should I be using match with define-type?