snoc

package module
v0.0.0-...-89d1eee Latest Latest
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 Go to latest Published: Sep 21, 2020 License: MIT Imports: 14 Imported by: 0

README

go-snoc

Simple LISP written in Go.

Currently uses a simple environment list for local variables, no fancy lexical bindng. NO I'M CHANGING THAT....

work in progress...

Right now go test should work:

[0]<---- (def pos 1)
---->   nil
[0]<---- (def neg -1)
---->   nil
[0]<---- (def zero 0)
---->   nil
[0]<---- (defun signum (x) (if (< x 0) neg (> x 0) pos zero))
---->   nil
[0]<---- (list (signum -888) (signum 0) (signum 123))
---->   (-1 0 1)
[0]<---- (list (list 1 2 3) (list 4 5 6))
---->   ((1 2 3) (4 5 6))
[0]<---- (let A (list 1 2 3) B (list 4 5 6) C (list A B) (list A B C))
---->   ((1 2 3) (4 5 6) ((1 2 3) (4 5 6)))
[0]<---- (defun my-triangle (x) (if (< x 1) 0 (+ x (my-triangle (- x 1)))))
---->   nil
[0]<---- (my-triangle 6)
---->   21
[0]<---- (defun my-length (x) (if (null? x) 0 (+ 1 (my-length (tail x)))))
---->   nil
[0]<---- (my-length (list 9 7 5 3 1))
---->   5
[0]<---- (defun my-descending (n) (if (<= n 0) (list) (cons n (my-descending (- n 1)))))
---->   nil
[0]<---- (my-descending 7)
---->   (7 6 5 4 3 2 1)
[0]<---- (defun my-descending (n) (if (<= n 0) (list) (cons n (my-descending (- n 1)))))
---->   nil
[0]<---- (defun my-sum (aList) (if (null? aList) 0 (+ (head aList) (my-sum (tail aList)))))
---->   nil
[0]<---- 111
[1]<---- 222
[2]<---- 333
---->   333
[0]<---- (my-sum (my-descending 100))
---->   5050

You can also use snoc.go to evaluate stdin:

$ echo '(defun !(x) (if (< x 1) 1 (* x (! (- x 1))))) (! 10)' | go run snoc.go 
[0]<---- (defun ! (x) (if (< x 1) 1 (* x (! (- x 1)))))
[1]<---- (! 10)
---->   3.6288e+06
2020/09/13 17:33:18 ==> result[0] = 3.6288e+06

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var (
	// Traditionally NIL would be a special *Sym,
	// but in this Lisp it will be a special *Pair.
	// It is not Interned.  The parser will have to know
	// about this special name.  AtomP(NIL) is still true,
	// although it cannot be used as an environment key.
	NIL   = &Pair{}         // Address matters; contents do not.
	FN    = Intern("fn")    // In other Lisps, this is lambda.
	TRUE  = Intern("true")  // In other Lisps, this is T or *T*.
	DEF   = Intern("def")   // Special to the REPL; it modifies the env.
	DEFUN = Intern("defun") // Special to the REPL; it modifies the env.
)
View Source 
var BuiltinFloatingBinaryOps = map[string]func(float64, float64) float64{
	"+":   func(a, b float64) float64 { return a + b },
	"-":   func(a, b float64) float64 { return a - b },
	"*":   func(a, b float64) float64 { return a * b },
	"div": func(a, b float64) float64 { return a / b },
	"mod": func(a, b float64) float64 { return math.Mod(a, b) },
}
View Source 
var BuiltinFloatingRelOps = map[string]func(float64, float64) bool{
	"<":  func(a, b float64) bool { return a < b },
	"<=": func(a, b float64) bool { return a <= b },
	"==": func(a, b float64) bool { return a == b },
	"!=": func(a, b float64) bool { return a != b },
	">":  func(a, b float64) bool { return a > b },
	">=": func(a, b float64) bool { return a >= b },
}
View Source 
var BuiltinPrims = map[string]func([]Any, *Env) Any{
	"call/cc": CallCC,
	"list": func(args []Any, env *Env) Any {
		z := NIL
		for i := len(args) - 1; i >= 0; i-- {
			z = Snoc(z, args[i])
		}
		return z
	},
	"null?": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return LispyBool(NullP(args[0]))
	},
	"atom?": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return LispyBool(AtomP(args[0]))
	},
	"eq": func(args []Any, env *Env) Any {
		MustLen(args, 2)
		return LispyBool(Eq(args[0], args[1]))
	},
	"head": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Head(args[0])
	},
	"tail": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Tail(args[0])
	},
	"1st": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Head(args[0])
	},
	"2nd": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Head(Tail(args[0]))
	},
	"3rd": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Head(Head(Tail(args[0])))
	},
	"4th": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Head(Head(Tail(Tail(args[0]))))
	},
	"5th": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Head(Head(Tail(Tail(Tail(args[0])))))
	},
	"eval": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return Eval(args[0], env)
	},
	"apply": func(args []Any, env *Env) Any {
		MustLen(args, 2)
		return Apply(args[0], ListToVec(args[1]), env)
	},
	"snoc": func(args []Any, env *Env) Any {
		MustLen(args, 2)
		p, ok := args[0].(*Pair)
		if !ok {
			Throw(args[0], "cannot Snoc")
		}
		return Snoc(p, args[1])
	},
	"cons": func(args []Any, env *Env) Any {
		MustLen(args, 2)
		p, ok := args[1].(*Pair)
		if !ok {
			Throw(args[1], "cannot Cons")
		}
		return Snoc(p, args[0])
	},
	"sum": func(args []Any, env *Env) Any {
		sum := 0.0
		for _, a := range args {
			sum += ToFloat(a)
		}
		return sum
	},
	"product": func(args []Any, env *Env) Any {
		product := 1.0
		for _, a := range args {
			product *= ToFloat(a)
		}
		return product
	},
}
View Source 
var BuiltinSpecials = map[string]func([]Any, *Env) Any{
	"quote": func(args []Any, env *Env) Any {
		MustLen(args, 1)
		return args[0]
	},
	"and": func(args []Any, env *Env) Any {
		z := Any(TRUE)
		for _, a := range args {
			x := Eval(a, env)
			if NullP(x) {
				return NIL
			}
			z = x
		}
		return z
	},
	"or": func(args []Any, env *Env) Any {
		for _, a := range args {
			x := Eval(a, env)
			if Bool(x) {
				return x
			}
		}
		return NIL
	},
	"all": func(args []Any, env *Env) Any {
		for _, a := range args {
			if NullP(Eval(a, env)) {
				return NIL
			}
		}
		return TRUE
	},
	"any": func(args []Any, env *Env) Any {
		for _, a := range args {
			if Bool(Eval(a, env)) {
				return TRUE
			}
		}
		return NIL
	},
	"if": func(args []Any, env *Env) Any {
		for len(args) >= 2 {
			pred := Eval(args[0], env)
			if Bool(pred) {
				return Eval(args[1], env)
			}
			args = args[2:]
		}
		MustEq(len(args), 1)
		return Eval(args[0], env)
	},
}
View Source 
var FlagVerbose = flag.Bool("v", false, "verbosity")
View Source 
var InternTable = make(map[string]*Sym)

var Globals = make(map[string]Any)

Functions

func AtomP 

func AtomP(o Any) bool

func Bool 

func Bool(o Any) bool

func Eq 

func Eq(o Any, a Any) bool

func ListLen 

func ListLen(a Any) int

func Log 

func Log(format string, args ...interface{})

func NullP 

func NullP(o Any) bool

func ParseExprs 

func ParseExprs(toks []Tok) (string, []Tok, []Any)

func Serial 

func Serial(prefix string) string

func Stringify 

func Stringify(o Any) string

func ToFloat 

func ToFloat(o Any) float64

func ToInt 

func ToInt(o Any) int

func ToStr 

func ToStr(o Any) string

Types

type Any 

type Any interface{}

func Apply 

func Apply(o Any, args []Any, env *Env) Any

func ApplyFunc 

func ApplyFunc(o *Func, args []Any, env *Env) Any

func ApplyPrim 

func ApplyPrim(o *Prim, args []Any, env *Env) Any

func ApplySpecial 

func ApplySpecial(o *Special, args []Any, env *Env) Any

func CallCC 

func CallCC(args []Any, env *Env) Any

func Eval 

func Eval(o Any, env *Env) Any

func EvalLambda 

func EvalLambda(params []Any, body Any, env *Env) Any

func Get 

func Get(o *Pair, key *Sym) (Any, bool)
func Head(o Any) Any

func LispyBool 

func LispyBool(b bool) Any

func ListToVec 

func ListToVec(a Any) []Any

func ParseFile 

func ParseFile(filename string) []Any

func ParseText 

func ParseText(text, filename string) []Any

func Repl 

func Repl(terp *Terp, r io.Reader) []Any

func Tail 

func Tail(o Any) Any

func Throw 

func Throw(o Any, format string, args ...interface{}) Any

func TryReplEval 

func TryReplEval(terp *Terp, xs []Any) (result Any, err interface{})

func TryReplParse 

func TryReplParse(s string) (xs []Any, ok bool)

func VecToList 

func VecToList(a []Any) Any

type ContinuationUsed 

type ContinuationUsed string // for exiting thread.

type Env 

type Env struct {
	Proto *ProtoFunc
	Up    *Env
	Slots []Any
	Terp  *Terp
}

func (*Env) String 

func (env *Env) String() string

type Func 

type Func struct {
	Outer  *Env
	Params []*Sym
	Values []Any // Only for Let
	Body   Any
	Name   string
	IsLet  bool
	Proto  *ProtoFunc
}

func (*Func) String 

func (o *Func) String() string

type Pair 

type Pair struct {
	H Any
	T *Pair
}

func Snoc 

func Snoc(o *Pair, a Any) *Pair

func (*Pair) String 

func (o *Pair) String() string

type Prim 

type Prim struct {
	Name string
	F    func(args []Any, env *Env) Any // args are evaluated.
}

func (*Prim) String 

func (o *Prim) String() string

type ProtoFunc 

type ProtoFunc struct {
	Outer  *ProtoFunc
	Params []*Sym
	Values []Any // Only for Let
	Body   Any
	Name   string
	IsLet  bool
}

func PreprocessFunc 

func PreprocessFunc(name string, params []*Sym, body Any, outer *ProtoFunc) (pf *ProtoFunc)

func (*ProtoFunc) String 

func (o *ProtoFunc) String() string

type Special 

type Special struct {
	Name string
	F    func(args []Any, env *Env) Any // args are unevaluated.
}

func (*Special) String 

func (o *Special) String() string

type Sym 

type Sym struct {
	S string
}

func Intern 

func Intern(s string) *Sym

func ListToVecOfSym 

func ListToVecOfSym(a Any) []*Sym

func (*Sym) String 

func (o *Sym) String() string

type Terp 

type Terp struct {
	Globals map[*Sym]Any
}

func NewTerp 

func NewTerp() *Terp

type Tok 

type Tok struct {
	Pos  scanner.Position
	Text string
}

func Lex 

func Lex(text, filename string) (z []Tok)

type Var 

type Var struct {
	Proto *ProtoFunc
	Slot  int
	Sym   *Sym
}

func (*Var) String 

func (o *Var) String() string

Source Files

View all Source files

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