Play with tinylisp at: https://daneelsan.github.io/tinylisp/
tinylisp is a minimal Lisp interpreter implemented in Zig, using NaN boxing for efficient memory representation. It supports core Lisp features like atoms, lists, conditionals, arithmetic, and closures, along with an interactive REPL and debugging tools for inspecting the heap, stack, and environment.
Read my thoughts at https://daneelsan.github.io/2025/03/20/tinylisp.html
#t (True):
λ #t
#tERR (Error):
λ (cdr 42)
ERR+ (Addition):
λ (+ 1 2 3 4)
10- (Subtraction):
λ (- 10 2 3)
5* (Multiplication):
λ (* 2 3 4)
24/ (Division):
λ (/ 3.4 4)
0.85car:
λ (car '(1 2 3))
1cdr:
λ (cdr '(1 2 3))
(2 3)cons:
λ (cons 1 2)
(1 . 2)λ (cons 1 '(2 3))
(1 2 3)' (Quoting):
λ '(+ 1 2 3)
(+ 1 2 3)eval (Evaluation):
λ (eval '(+ 1 2 3))
6if:
λ (if (< 1 2) 'true 'false)
trueand:
λ (and (< 1 2) (< 2 3))
#tλ (and (< 2 1) (< 2 3))
()or:
λ (or (< 1 2) (< 3 2))
#tnot:
λ (not (< 1 2))
()= (Equality):
λ (= 1.0 1)
#tλ (= 1.1 1)
()lambda:
λ ((lambda (x) (* x x)) 5)
25define:
λ (define square (lambda (x) (* x x)))
squareλ (square 5)
25λ (define x 42)
xλ (+ x x)
84echo:
λ (+ (echo (* 3 4) 5))
>> 12
12echo-eval:
λ (echo-eval (+ (* 3 4) 5))
>> ((+ (* 3 4) 5))
<< 17
17print-env:
λ (print-env)
(
(echo-eval . «echo-eval»)
(echo . «echo»)
(print-env . «print-env»)
(print-stack . «print-stack»)
(print-heap . «print-heap»)
(define . «define»)
(lambda . «lambda»)
(if . «if»)
(and . «and»)
(or . «or»)
(not . «not»)
(= . «=»)
(> . «>»)
(< . «<»)
(/ . «/»)
(* . «*»)
(- . «-»)
(+ . «+»)
(int . «int»)
(cdr . «cdr»)
(car . «car»)
(cons . «cons»)
(quote . «quote»)
(eval . «eval»)
(#t . #t)
)
()print-heap:
λ (print-heap)
------------------- HEAP -------------------
| # | address | symbol |
|-----|----------|-------------------------|
| 0 | 0x0000 | ERR |
| 1 | 0x0004 | #t |
| 2 | 0x0007 | eval |
| 3 | 0x000C | quote |
| 4 | 0x0012 | cons |
| 5 | 0x0017 | car |
| 6 | 0x001B | cdr |
| 7 | 0x001F | int |
| 8 | 0x0023 | + |
| 9 | 0x0025 | - |
| 10 | 0x0027 | * |
| 11 | 0x0029 | / |
| 12 | 0x002B | < |
| 13 | 0x002D | > |
| 14 | 0x002F | = |
| 15 | 0x0031 | not |
| 16 | 0x0035 | or |
| 17 | 0x0038 | and |
| 18 | 0x003C | if |
| 19 | 0x003F | lambda |
| 20 | 0x0046 | define |
| 21 | 0x004D | print-heap |
| 22 | 0x0058 | print-stack |
| 23 | 0x0064 | print-env |
| 24 | 0x006E | echo |
| 25 | 0x0073 | echo-evaluation |
| ... |
--------------------------------------------
()print-stack:
λ (print-stack)
------------- STACK ------------
| pointer | tag | ordinal | Expr
|----------|--------|----------|--------------
| 1024 | ATOM | 0x0004 | #t
| 1023 | ATOM | 0x0004 | #t
| 1022 | CONS | 1022 |
| 1021 | NIL | 0 | ()
| 1020 | ATOM | 0x0007 | eval
| 1019 | PRIM | 0 | «eval»
| 1018 | CONS | 1018 |
| 1017 | CONS | 1020 |
| 1016 | ATOM | 0x000C | quote
| 1015 | PRIM | 1 | «quote»
| 1014 | CONS | 1014 |
| 1013 | CONS | 1016 |
| 1012 | ATOM | 0x0012 | cons
| 1011 | PRIM | 2 | «cons»
| 1010 | CONS | 1010 |
| 1009 | CONS | 1012 |
| 1008 | ATOM | 0x0017 | car
| 1007 | PRIM | 3 | «car»
| 1006 | CONS | 1006 |
| 1005 | CONS | 1008 |
| 1004 | ATOM | 0x001B | cdr
| 1003 | PRIM | 4 | «cdr»
| 1002 | CONS | 1002 |
| 1001 | CONS | 1004 |
| 1000 | ATOM | 0x001F | int
| 999 | PRIM | 5 | «int»
| 998 | CONS | 998 |
| 997 | CONS | 1000 |
| 996 | ATOM | 0x0023 | +
| 995 | PRIM | 6 | «+»
| 994 | CONS | 994 |
| 993 | CONS | 996 |
| 992 | ATOM | 0x0025 | -
| 991 | PRIM | 7 | «-»
| 990 | CONS | 990 |
| 989 | CONS | 992 |
| 988 | ATOM | 0x0027 | *
| 987 | PRIM | 8 | «*»
| 986 | CONS | 986 |
| 985 | CONS | 988 |
| 984 | ATOM | 0x0029 | /
| 983 | PRIM | 9 | «/»
| 982 | CONS | 982 |
| 981 | CONS | 984 |
| 980 | ATOM | 0x002B | <
| 979 | PRIM | 10 | «<»
| 978 | CONS | 978 |
| 977 | CONS | 980 |
| 976 | ATOM | 0x002D | >
| 975 | PRIM | 11 | «>»
| 974 | CONS | 974 |
| 973 | CONS | 976 |
| 972 | ATOM | 0x002F | =
| 971 | PRIM | 12 | «=»
| 970 | CONS | 970 |
| 969 | CONS | 972 |
| 968 | ATOM | 0x0031 | not
| 967 | PRIM | 13 | «not»
| 966 | CONS | 966 |
| 965 | CONS | 968 |
| 964 | ATOM | 0x0035 | or
| 963 | PRIM | 14 | «or»
| 962 | CONS | 962 |
| 961 | CONS | 964 |
| 960 | ATOM | 0x0038 | and
| 959 | PRIM | 15 | «and»
| 958 | CONS | 958 |
| 957 | CONS | 960 |
| 956 | ATOM | 0x003C | if
| 955 | PRIM | 16 | «if»
| 954 | CONS | 954 |
| 953 | CONS | 956 |
| 952 | ATOM | 0x003F | lambda
| 951 | PRIM | 17 | «lambda»
| 950 | CONS | 950 |
| 949 | CONS | 952 |
| 948 | ATOM | 0x0046 | define
| 947 | PRIM | 18 | «define»
| 946 | CONS | 946 |
| 945 | CONS | 948 |
| 944 | ATOM | 0x004D | print-heap
| 943 | PRIM | 19 | «print-heap»
| 942 | CONS | 942 |
| 941 | CONS | 944 |
| 940 | ATOM | 0x0058 | print-stack
| 939 | PRIM | 20 | «print-stack»
| 938 | CONS | 938 |
| 937 | CONS | 940 |
| 936 | ATOM | 0x0064 | print-env
| 935 | PRIM | 21 | «print-env»
| 934 | CONS | 934 |
| 933 | CONS | 936 |
| 932 | ATOM | 0x006E | echo
| 931 | PRIM | 22 | «echo»
| 930 | CONS | 930 |
| 929 | CONS | 932 |
| 928 | ATOM | 0x0073 | echo-eval
| 927 | PRIM | 23 | «echo-eval»
| 926 | CONS | 926 |
| 925 | CONS | 928 |
| 924 | ATOM | 0x0058 | print-stack
| 923 | NIL | 0 | ()
| ... |
|------------------------------|
()Compiled using zig version:
$ zig version
0.14.0Build the wasm executable using zig build:
$ zig build
$ ls zig-out/bin
tinylisp.wasmAdditionally, build the local executable using zig build local:
$ zig build local
$ ls zig-out/bin
tinylisp tinylisp.wasmOr run the local executable directly using zig build run:
$ zig build run
λ - Compile to .wasm and add a javascript REPL
- Write a blogpost
- Expand documentation with more examples
- Add tests
- Improve parsing to handle multiple expressions separed by new lines
-
Ctrl+cto delete the current line - Multiline inputs don't work well with the history explorer (
Up Arrow) - Syntax highlighting
- Drop files
- Click to copy input/output