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slisp

Lisp is a functional language with a long history and Scheme is one of the two main dialects of Lisp. slisp is a simple interpreter implementation implenmentation of Scheme covered in SICP with C language. It may can't pass the standard Scheme interpreter test such as R6RS. It just a toy language for fun and study.

###1.Data type slisp support boolean,int,float,symbol and pair.Every data type has it's corresponding operation.

boolean. It's represented by the value #t,#T,#f,#F. It supports logic operations 'and','or','not' and the relation operations '>' '>=' '<' '<=' '==' return boolean type value.
int,float. It supports arithmatic operations '+','-','*','/','%' and relation operation '>' '>=' '<' '<=' '=='. In arithmatic operations, if all are int, it will return int type value; otherwise, it will return float type value.
symbol.
pair. It supoorts 'cons','car','cdr' operations.

###2.Variables The style of identifier of variables is C-like, not Scheme. It starts with alpha and '' and the following can be alpha,number and ''. You can define a variable with the 'define' procedure.

###3.Control flow

slisp support 'if' 'cond' expression to make choice. It is describled in SICP.
slisp support recursion (not tail recursion).You can implementation iteration with the recursion way.
slisp also support to define function.It is also describled in SICP.

###4.Examples

Expressions:

66
;value: 66
(+ 137 349)
;value: 486
(+ 10 5)
;value: 2
'a
;value: a
''a
;value: (quote a)
(define (abs x)
  (if (< x 0)
      (- x)
      x))
;value: ()
(abs 3)
;value: 3
(define (abs x)
  (cond ((< x 0)(- x))
      (else x)))
;value: ()
(abs 3)
;value: 3
(abs (- 3))
;value: -3

Define variable and procedure:

(define size 2)
;value: ()
size
;value: 2
(define (square x) (* x x))
;value: ()
(square 1024)
;value: 1048576

Recursion:

(define (factorial n)
  (if (== n 1)
      1
      (* n (factorial (- n 1)))))
;value: ()
(factorial 9)
;value: 362880

###5.Problems The main problem is data type and error handle. It is the work to deal with.

slisp can support many(I can't test all) examples of Scheme code in SICP. I think it's will be better!