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mal/logo/step4_if_fn_do.lg
Dov Murik 4eb88ef295 Logo implementation
Tested on UCBLogo 6.0 with some minor tweaks (for performance and adding
a `timems` function).  The tweaks are performed during Docker image
creation (see Dockerfile).

Tests of step 5 are skipped because UCBLogo is too slow.

Interop is available via `(logo-eval "logo code to run")`.

The `examples` directory contains a Mal example of drawing a tree using
turtle graphics.
2016-06-17 16:36:09 -04:00

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load "../logo/readline.lg
load "../logo/reader.lg
load "../logo/printer.lg
load "../logo/types.lg
load "../logo/env.lg
load "../logo/core.lg
to _read :str
output read_str :str
end
to eval_ast :ast :env
output case (obj_type :ast) [
[[symbol] env_get :env :ast]
[[list] obj_new "list map [_eval ? :env] obj_val :ast]
[[vector] obj_new "vector map [_eval ? :env] obj_val :ast]
[[hashmap] obj_new "hashmap map [_eval ? :env] obj_val :ast]
[else :ast]
]
end
to _eval :ast :env
if (obj_type :ast) <> "list [output eval_ast :ast :env]
if emptyp obj_val :ast [output :ast]
localmake "a0 nth :ast 0
case list obj_type :a0 obj_val :a0 [
[[[symbol def!]]
localmake "a1 nth :ast 1
localmake "a2 nth :ast 2
output env_set :env :a1 _eval :a2 :env ]
[[[symbol let*]]
localmake "a1 nth :ast 1
localmake "letenv env_new :env [] []
localmake "i 0
while [:i < _count :a1] [
ignore env_set :letenv nth :a1 :i _eval nth :a1 (:i + 1) :letenv
make "i (:i + 2)
]
output _eval nth :ast 2 :letenv ]
[[[symbol do]]
output last obj_val eval_ast rest :ast :env ]
[[[symbol if]]
localmake "a1 nth :ast 1
localmake "cond _eval :a1 :env
output case obj_type :cond [
[[nil false] ifelse (_count :ast) > 3 [
_eval nth :ast 3 :env
] [
nil_new
]]
[else _eval nth :ast 2 :env]
]]
[[[symbol fn*]]
output fn_new nth :ast 1 :env nth :ast 2 ]
[else
localmake "el eval_ast :ast :env
localmake "f nth :el 0
case obj_type :f [
[[nativefn]
output apply obj_val :f butfirst obj_val :el ]
[[fn]
localmake "funcenv env_new fn_env :f fn_args :f rest :el
output _eval fn_body :f :funcenv ]
[else
(throw "error [Wrong type for apply])]
] ]
]
end
to _print :exp
output pr_str :exp "true
end
to re :str
output _eval _read :str :repl_env
end
to rep :str
output _print re :str
end
to repl
localmake "running "true
while [:running] [
localmake "line readline word "user> :space_char
ifelse :line=[] [
print "
make "running "false
] [
if not emptyp :line [
catch "error [print rep :line]
localmake "exception error
if not emptyp :exception [
(print "Error: first butfirst :exception)
]
]
]
]
end
make "repl_env env_new [] [] []
foreach :core_ns [
ignore env_set :repl_env first ? first butfirst ?
]
; core.mal: defined using the language itself
ignore re "|(def! not (fn* (a) (if a false true)))|
repl
bye