Add standard env

Python3/lisp.py

@@ -1,7 +1,9 @@
-## (c) Peter Norvig, 2010-16; See http://norvig.com/lispy.html
+# (c) Peter Norvig, 2010-16; See http://norvig.com/lispy.html
+import math
+import operator as op
 
 program = "(begin (define r 10) (* pi (* r r)))"
-################ Types
+# Types
 
 Symbol = str
 List = list
@@ -10,16 +12,19 @@ Atom = (Symbol, Number)
 Exp = (Atom, list)
 Env = dict
 
-################ Parsing: parse, tokenize, and read_from_tokens
+# Parsing: parse, tokenize, and read_from_tokens
+
 
 def parse(program: str) -> Exp:
     "Read a Scheme expression from a string."
     return read_from_tokens(tokenize(program))
 
+
 def tokenize(chars: str) -> list:
     "Convert a string of characters into list of tokens."
     return chars.replace('(', ' ( ').replace(')', ' ) ').split()
 
+
 def read_from_tokens(tokens: list) -> Exp:
     "Read an expression from a sequence of tokens."
     if len(tokens) == 0:
@@ -36,12 +41,49 @@ def read_from_tokens(tokens: list) -> Exp:
     else:
         return atom(token)
 
+
 def atom(token: str) -> Atom:
     "Numbers become numbers; every other token is a symbol."
-    try: return int(token)
+    try:
+        return int(token)
     except ValueError:
-        try: return float(token)
+        try:
+            return float(token)
         except ValueError:
             return Symbol(token)
 
-print(parse(program))
+# Environments
+def standard_env() -> Env:
+    'An environment with some Scheme standard procedures'
+    env = Env()
+    env.update(vars(math))
+    env.update({
+        '+': op.add, '-': op.sub, '*': op.mul, '/': op.truediv,
+        '>': op.gt, '<': op.lt, '>=': op.ge, '<=': op.le, '=': op.eq,
+        'abs': abs,
+        'append': op.add,
+        'apply': lambda proc, args: proc(args),
+        'begin': lambda *x: x[-1],
+        'car': lambda x: x[0],
+        'cdr': lambda x: x[1:],
+        'cons': lambda x, y: [x]+y,
+        'eq?': op.is_,
+        'equal?': op.eq,
+        'expt': pow,
+        'length': len,
+        'list': lambda *x: list(x),
+        'list?': lambda x: isinstance(x, List),
+        'map': map,
+        'max': max,
+        'min': min,
+        'not': op.not_,
+        'null?': lambda x: x == [],
+        'number?': lambda x : isinstance(x, Number),
+        'print': print,
+        'procedure?': callable,
+        'round': round,
+        'symbol?': lambda x : isinstance(x, Symbol)
+    })
+    return env
+
+global_env = standard_env()

TypeScript/lisp.ts

@@ -1,19 +1,51 @@
 // Lispts: Scheme Interpreter in TypeScript
+
 const program = "(begin (define r 10) (* pi (* r r)))"
 
-type LSymbol = string // A Lisp Symbol(alias TSymbol) is implemented as TypeScript string
+// types
+type LSymbolType = string // A Lisp Symbol(alias TSymbol) is implemented as TypeScript string
 type LNumber = number // A Lisp Symbol(alias TSymbol) is implemented as TypeScript number
-type Atom = LSymbol | number // A Lisp Atom is a Symbol or Number impl
+type Atom = LSymbolType | number // A Lisp Atom is a Symbol or Number impl
 type List = Array<any> // A Lisp List is implemented as a TypeScript array
 type Exp = Atom | List // A Lisp expression is an Atom or List
-interface Env {
+type Env = Map<string, any>;
-  [key: string | number]: any
+
-} // A Lisp environment is a mapping of {variable: value}
+class LSymbol {
+  readonly value: string;
+
+  constructor(value: string) {
+    this.value = value;
+  }
+
+  toString(): string {
+    return this.value;
+  }
+}
+
+// utils
+const deepEqual = (a: any, b: any): boolean =>{
+  if(a=== b) return true
+
+  if(typeof a !== 'object'|| typeof b !== 'object' || a === null || b === null )
+  return false
+
+  const keyA = Object.keys(a)
+  const keyB = Object.keys(b)
+
+  if(keyA.length !== keyB.length) return false
+
+
+  for(const key of keyA){
+    if(!keyB.includes(key) || !deepEqual(a[key], b[key])) return false
+  }
+  
+  return true
+}
 
 /**
  * Read a Scheme expression from a string.
  */
-const parse = (program: string): Exp => read_from_tokens(tokenize(program))
+const parse = (program: string): Exp => readFromTokens(tokenize(program))
 
 /**
  * Convert a string into a list of tokens.
@@ -29,20 +61,20 @@ const tokenize = (char: string): string[] =>
  * Numbers become numbers; every other token is a symbol(LSymbol).
  */
 const atom = (token: string): Atom =>
-  Number.isNaN(token) ? Number(token) : (token as LSymbol)
+  isNaN(Number(token)) ? token as LSymbolType : Number(token)
 
   /**
  * Read an expression from a sequence of tokens
  */
-const read_from_tokens = (tokens: string[]): Exp => {
+const readFromTokens = (tokens: string[]): Exp => {
-  if (tokens.length === 0 || !tokens) {
+  if (tokens.length === 0) {
     throw new Error('unexpected EOF while reading')
   }
   const token = tokens.shift()
   if (token === '(') {
     const l = []
     while (tokens[0] !== ')') {
-      l.push(read_from_tokens(tokens))
+      l.push(readFromTokens(tokens))
     }
     tokens.shift()
     return l
@@ -53,4 +85,45 @@ const read_from_tokens = (tokens: string[]): Exp => {
   }
 }
 
-console.log(parse(program))
+// Environments
+/**
+ * An environment with some Scheme standard procedures
+ */
+const standardEnv = (): Env => {
+  let env: Env = new Map()
+  env.set('+', (a: number, b: number) => a + b)
+  env.set('-', (a: number, b: number) => a - b)
+  env.set('*', (a: number, b: number) => a * b)
+  env.set('/', (a: number, b: number) => a / b)
+  env.set('>', (a: number, b: number) => a > b)
+  env.set('<', (a: number, b: number) => a < b)
+  env.set('>=', (a: number, b: number) => a >= b)
+  env.set('<=', (a: number, b: number) => a <= b)
+  env.set('=', (a: number, b: number) => a === b)
+  env.set('abs', Math.abs)
+  env.set('append', (a: any[], b: any[]) => a.concat(b))
+  env.set('apply', (proc: Function, args: any[]) => proc(...args))
+  env.set('begin', (...x: any) => x[x.length - 1])
+  env.set('car', (...x: any) => x[0])
+  env.set('cdr', (...x: any) => x.slice(1))
+  env.set('cons', (x: any, y: any) => [x, ...y])
+  env.set('eq?', (a: any, b: any) => Object.is(a, b))
+  env.set('equal?', (a: any, b: any) => deepEqual(a, b))
+  env.set('expt', Math.pow)
+  env.set('length', (x: any[]) => x.length)
+  env.set('list', (...x: any[]) => Array.from(x))
+  env.set('list?', (x: any) => Array.isArray(x))
+  env.set('map', Array.prototype.map)
+  env.set('max', Math.max)
+  env.set('min', Math.min)
+  env.set('not', (x: boolean) => !x)
+  env.set('null?', (x: any[]) => x.length === 0)
+  env.set('number?', (x: any) => typeof x === 'number')
+  env.set('print', console.log)
+  env.set('procedure?', (x: any) => typeof x === 'function')
+  env.set('round', Math.round)
+  env.set('symbol?', (x: any) =>x instanceof LSymbol )
+  return env
+}
+
+const globalEnv = standardEnv()