Parses list.squig

6 files changed, 618 insertions, 63 deletions

diff --git a/ast.cpp b/ast.cpp
index e69de29..d1742e2 100644
--- a/ast.cpp
+++ b/ast.cpp
@@ -0,0 +1,207 @@
+#include "ast.h"
+
+using namespace std;
+
+
+static int indent_level_index=ios_base::xalloc();
+
+
+namespace std{
+	string to_string(Expression::Type type){
+		switch(type){
+			case Expression::Type::binop: return "binop";
+			case Expression::Type::unop: return "unop";
+			case Expression::Type::call: return "call";
+			case Expression::Type::dive: return "dive";
+			case Expression::Type::number: return "number";
+			case Expression::Type::string: return "string";
+			case Expression::Type::scope: return "scope";
+			default: return to_string((int)type);
+		}
+	}
+
+	string to_string(Statement::Type type){
+		switch(type){
+			case Statement::Type::create: return "create";
+			case Statement::Type::assign: return "assign";
+			case Statement::Type::expression: return "expression";
+			default: return to_string((int)type);
+		}
+	}
+}
+
+
+Site::Site():lnum(-1),linex(-1){}
+Site::Site(const string &filename,i64 lnum,i64 linex)
+	:filename(filename),lnum(lnum),linex(linex){}
+
+Site Site::addX(i64 dx){
+	return Site(filename,lnum,linex+dx);
+}
+
+ostream& operator<<(ostream &os,Site site){
+	return os<<site.filename<<':'<<site.lnum<<':'<<site.linex;
+}
+
+
+Scope::Scope():type(Type::direct){}
+Scope::Scope(Type type,const StatementList &body,const vector<Expression> &args)
+	:type(type),body(body),args(args){}
+/*Scope::Scope(Type type,const StatementList &body,const vector<Name> &nameargs)
+		:type(type),body(body){
+	for(const Name &n : nameargs){
+		args.emplace_back(Expression::Type::call,n,vector<Expression>());
+	}
+}*/
+
+string indent(int amount){
+	return string(amount*4,' ');
+}
+
+ostream& operator<<(ostream &os,const Scope &scope){
+	switch(scope.type){
+		case Scope::Type::direct: break;
+		case Scope::Type::lazy: os<<'?'; break;
+		case Scope::Type::function: os<<"??"; break;
+	}
+	if(scope.args.size()!=0){
+		os<<'(';
+		bool first=true;
+		for(const Expression &ex : scope.args){
+			if(!first)os<<", ";
+			else first=false;
+			os<<ex;
+		}
+		os<<')';
+	}
+	os<<"{\n";
+	os.iword(indent_level_index)++;
+	int level=os.iword(indent_level_index);
+	
+	os<<scope.body;
+
+	os.iword(indent_level_index)--;
+	return os<<'\n'<<indent(level)<<'}';
+}
+
+
+Expression::Expression(Type type,const Name &name,const vector<Expression> &args)
+		:type(type),name(name),args(args){
+	if(type!=Type::binop&&type!=Type::call){
+		throw runtime_error("Expression(type,name,args) called with invalid type "+to_string(type));
+	}
+}
+Expression::Expression(Type type,const Name &name,const Expression &arg)
+		:type(type),name(name),args({arg}){
+	if(type!=Type::unop){
+		throw runtime_error("Expression(type,name,arg) called with invalid type "+to_string(type));
+	}
+}
+Expression::Expression(Type type,const Name &name,const vector<Expression> &args,const Scope &scope)
+		:type(type),name(name),args(args),scope(scope){
+	if(type!=Type::dive){
+		throw runtime_error("Expression(type,name,args,scope) called with invalid type "+to_string(type));
+	}
+}
+Expression::Expression(Type type,double numval)
+		:type(type),numval(numval){
+	if(type!=Type::number){
+		throw runtime_error("Expression(type,numval) called with invalid type "+to_string(type));
+	}
+}
+Expression::Expression(Type type,const string &strval)
+		:type(type),strval(strval){
+	if(type!=Type::string){
+		throw runtime_error("Expression(type,strval) called with invalid type "+to_string(type));
+	}
+}
+Expression::Expression(Type type,const Scope &scope)
+		:type(type),scope(scope){
+	if(type!=Type::scope){
+		throw runtime_error("Expression(type,scope) called with invalid type "+to_string(type));
+	}
+}
+Expression::Expression(Type type,const vector<Expression> &args)
+		:type(type),args(args){
+	if(type!=Type::cond){
+		throw runtime_error("Expression(type,args) called with invalid type "+to_string(type));
+	}
+}
+
+ostream& operator<<(ostream &os,const Expression &expr){
+	switch(expr.type){
+		case Expression::Type::binop:
+			return os<<'('<<expr.args[0]<<' '<<expr.name<<' '<<expr.args[1]<<')';
+
+		case Expression::Type::unop:
+			return os<<expr.name<<expr.args[0];
+
+		case Expression::Type::call:
+		case Expression::Type::dive:
+			os<<expr.name;
+			if(expr.args.size()!=0){
+				os<<'(';
+				bool first=true;
+				for(const auto &a : expr.args){
+					if(!first)os<<", ";
+					else first=false;
+					os<<a;
+				}
+				os<<')';
+			}
+			if(expr.type==Expression::Type::dive){
+				os<<expr.scope;
+			}
+			return os;
+
+		case Expression::Type::number:
+			return os<<expr.numval;
+
+		case Expression::Type::string:
+			return os<<expr.strval;
+
+		case Expression::Type::scope:
+			throw runtime_error("operator<< on Expression:scope not implemented");
+
+		case Expression::Type::cond:
+			return os<<"if "<<expr.args[0]<<" then "<<expr.args[1]<<" else "<<expr.args[2];
+	}
+}
+
+
+Statement::Statement(Type type,const Name &dstvar,const Expression &expr)
+		:type(type),dstvar(dstvar),expr(expr){
+	if(type!=Type::create&&type!=Type::assign){
+		throw runtime_error("Statement(type,dstvar,expr) called with invalid type "+to_string(type));
+	}
+}
+Statement::Statement(Type type,const Expression &expr)
+		:type(type),expr(expr){
+	if(type!=Type::expression){
+		throw runtime_error("Statement(type,expr) called with invalid type "+to_string(type));
+	}
+}
+
+
+ostream& operator<<(ostream &os,const Statement &st){
+	switch(st.type){
+		case Statement::Type::create:
+			return os<<st.dstvar<<" := "<<st.expr;
+
+		case Statement::Type::assign:
+			return os<<st.dstvar<<" = "<<st.expr;
+
+		case Statement::Type::expression:
+			return os<<st.expr;
+	}
+}
+
+ostream& operator<<(ostream &os,const StatementList &stl){
+	bool first=true;
+	for(const Statement &st : stl){
+		if(!first)os<<'\n'<<indent(os.iword(indent_level_index));
+		else first=false;
+		os<<st;
+	}
+	return os;
+}
diff --git a/ast.h b/ast.h
index 78abd55..de30d5a 100644
--- a/ast.h
+++ b/ast.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <iostream>
 #include <string>
 #include <vector>
 #include "global.h"
@@ -8,6 +9,7 @@ using namespace std;
 
 
 class Statement;
+class Expression;
 using Name = string;
 using StatementList = vector<Statement>;
 
@@ -18,37 +20,45 @@ public:
 
 	Site();
 	Site(const string &filename,i64 lnum,i64 linex);
+
+	Site addX(i64 dx);
 };
 
+ostream& operator<<(ostream &os,Site site);
+
 class Scope{
 public:
 	enum class Type{
 		direct,
 		lazy,
 		function,
-		async,
+		// async,
 	};
 
 	Type type;
 	StatementList body;
-	vector<Name> args;
+	vector<Expression> args;
 
 	Site site;
 
 	Scope();
-	Scope(Type type,const StatementList &body,const vector<Name> &args);
+	Scope(Type type,const StatementList &body,const vector<Expression> &args);
+	// Scope(Type type,const StatementList &body,const vector<Name> &args);
 };
 
+ostream& operator<<(ostream &os,const Scope &scope);
+
 class Expression{
 public:
 	enum class Type{
 		binop,  // name, args[0], args[1]
 		unop,  // name, args[0]
-		call,  // name, args
-		dive,  // name, args, body
+		call,  // name, args         -- variable reference when args={}
+		dive,  // name, args, scope  -- variable dive when args={}
 		number,  // numval
 		string,  // strval
 		scope,  // scope
+		cond,  // args[0] (cond), args[1] (then), args[2] (else)
 	};
 
 	Type type;
@@ -57,19 +67,21 @@ public:
 	double numval;
 	string strval;
 	Scope scope;
-	StatementList body;
 
 	Site site;
 
-	Expression();
+	// Expression();
 	Expression(Type type,const Name &name,const vector<Expression> &args);  // binop, call
 	Expression(Type type,const Name &name,const Expression &arg);  // unop
-	Expression(Type type,const Name &name,const vector<Expression> &args,const StatementList &body);  // dive
+	Expression(Type type,const Name &name,const vector<Expression> &args,const Scope &scope);  // dive
 	Expression(Type type,double numval);  // number
 	Expression(Type type,const string &strval);  // string
 	Expression(Type type,const Scope &scope);  // scope
+	Expression(Type type,const vector<Expression> &args);  // cond
 };
 
+ostream& operator<<(ostream &os,const Expression &expr);
+
 class Statement{
 public:
 	enum class Type{
@@ -88,3 +100,6 @@ public:
 	Statement(Type type,const Name &dstvar,const Expression &expr);  // create, assign
 	Statement(Type type,const Expression &expr);  // expr
 };
+
+ostream& operator<<(ostream &os,const Statement &st);
+ostream& operator<<(ostream &os,const StatementList &stl);
diff --git a/list.squig b/list.squig
index ea0d333..b08dafd 100644
--- a/list.squig
+++ b/list.squig
@@ -1,11 +1,13 @@
-new_list := ??{
-	front := nil
-	back := nil
+list_new := ??{
+	x := {
+		front := nil
+		back := nil
+	}
 }
 
 list_push_front := ??(list, item){
 	list {
-		if front == nil {
+		if front == nil then {
 			front = {
 				value := item
 				next := nil
@@ -24,7 +26,7 @@ list_push_front := ??(list, item){
 
 list_push_back := ??(list, item){
 	list {
-		if back == nil {
+		if back == nil then {
 			front = {
 				value := item
 				next := nil
@@ -44,67 +46,59 @@ list_push_back := ??(list, item){
 list_pop_front := ??(list){
 	x := nil
 	list {
-		if front == nil {
+		if front == nil then {
 			throw_error("Call to 'list_pop_front' on empty list")
-		}
+		} else {}
 		front {
 			x = value
 			front = next
 		}
-		if front == nil {
+		if front == nil then {
 			back = nil
-		}
+		} else {}
 	}
 }
 
 list_pop_back := ??(list){
 	x := nil
 	list {
-		if back == nil {
+		if back == nil then {
 			throw_error("Call to 'list_pop_back' on empty list")
-		}
+		} else {}
 		back {
 			x = value
 			back = prev
 		}
-		if back == nil {
+		if back == nil then {
 			front = nil
-		}
+		} else {}
 	}
 }
 
 list_get := nil
 {
 	get_helper := ??(front, idx){
-		if front == nil {
+		if front == nil then {
 			throw_error("Index past end of list in 'list_get'")
-		}
+		} else {}
 		x := nil
-		if idx == 0 {
+		if idx == 0 then {
 			front {
 				x = value
 			}
 		} else {
 			front {
-				found := nil
-				get_helper(next, idx - 1){
-					found = x
-				}
-				x = found
+				x = get_helper(next, idx - 1)
 			}
 		}
 	}
 	list_get = ??(list, idx){
-		if idx < 0 {
+		if idx < 0 then {
 			throw_error("Negative index in 'list_get'")
-		}
+		} else {}
 		x := nil
 		list {
-			found := nil
-			get_helper(front, idx){
-				found = x
-			}
-			x = found
+			x = get_helper(front, idx)
 		}
 	}
 }
@@ -112,23 +106,23 @@ list_get := nil
 list_set := nil
 {
 	set_helper := ??(front, idx, val){
-		if front == nil {
+		if front == nil then {
 			throw_error("Index past end of list in 'list_set'")
-		}
-		if idx == 0 {
+		} else {}
+		if idx == 0 then {
 			front {
 				value = val
 			}
 		} else {
 			front {
-				set_helper(next, idx - 1, val){}
+				set_helper(next, idx - 1, val)
 			}
 		}
 	}
 	list_set = ??(list, idx, val){
-		if idx < 0 {
+		if idx < 0 then {
 			throw_error("Negative index in 'list_set'")
-		}
+		} else {}
 		list {
 			set_helper(front, idx, val)
 		}
diff --git a/main.cpp b/main.cpp
index b28e446..f8b9681 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,11 +1,48 @@
 #include <iostream>
+#include <fstream>
+#include <cstring>
 #include "parser.h"
 
 using namespace std;
 
 
+string readstream(istream &in){
+	string res;
+	char buf[4096];
+	while(true){
+		in.read(buf,sizeof(buf));
+		if(in.gcount()==0)break;
+		res.append(buf,in.gcount());
+	}
+	return res;
+}
+
 int main(int argc,char **argv){
-	(void)argc;
-	(void)argv;
+	string source,filename;
+	bool fromstdin=false;
+	if(argc==1)fromstdin=true;
+	else if(argc==2){
+		if(strcmp(argv[1],"-")==0)fromstdin=true;
+		else filename=argv[1];
+	} else {
+		cerr<<"Pass source on stdin, or filename as argument (or '-' for stdin)"<<endl;
+		return 1;
+	}
+	if(fromstdin){
+		source=readstream(cin);
+		filename="<stdin>";
+	} else {
+		ifstream f(filename);
+		source=readstream(f);
+	}
+
+	StatementList stl;
+	try {
+		stl=parse(source,filename);
+	} catch(ParseError e){
+		cerr<<e.what()<<endl;
+		return 1;
+	}
+	cout<<stl<<endl;
 	return 0;
 }
diff --git a/parser.cpp b/parser.cpp
index 56fb035..54b0c0c 100644
--- a/parser.cpp
+++ b/parser.cpp
@@ -1,5 +1,6 @@
 #include <stdexcept>
 #include <stack>
+#include <unordered_map>
 #include <cstring>
 #include <cctype>
 #include <cassert>
@@ -8,10 +9,27 @@
 using namespace std;
 
 
+#define DEBUG cerr<<'['<<__FILE__<<':'<<__LINE__<<"] "
+
+template <typename T>
+static ostream& operator<<(ostream &os,const vector<T> &v){
+	os<<'{';
+	bool first=true;
+	for(const T &t : v){
+		if(!first)os<<", ";
+		else first=false;
+		os<<t;
+	}
+	return os<<'}';
+}
+
+
 ParseError::ParseError(const string &what_arg)
 	:runtime_error(what_arg){}
 ParseError::ParseError(const char *what_arg)
 	:runtime_error(what_arg){}
+ParseError::ParseError(Site site,const string &what_arg)
+	:runtime_error(site.filename+":"+to_string(site.lnum)+":"+to_string(site.linex)+": "+what_arg){}
 
 
 static bool isinitwordchar(char c){
@@ -27,7 +45,7 @@ static const vector<string> tok_symbols={
 	":=", "=",
 	"+", "-", "*", "/", "%",
 	"(", ")", ",",
-	"{", "}", "?{", "??{", "}&",
+	"{", "}", "?", "??",
 };
 
 static bool isSymbolPrefix(const string &s){
@@ -108,6 +126,10 @@ public:
 		return *this;
 	}
 
+	Site site() const {
+		return Site(filename,lnum,linex);
+	}
+
 	/*void save(){
 		statestack.push({idx,nextidx,lnum,lineidx,ttype});
 	}
@@ -131,7 +153,7 @@ public:
 	}
 
 	Token get(){
-		return Token(ttype,get_(),Site(filename,lnum,linex));
+		return Token(ttype,get_(),site());
 	}
 
 	// Returns whether there are more tokens
@@ -144,7 +166,7 @@ public:
 				lnum++;
 				linex=1;
 			} else {
-				linex++;
+				linex+=1+3*(source[idx]=='\t');
 			}
 			idx++;
 		}
@@ -158,7 +180,7 @@ public:
 					ttype=Token::Type::terminator;
 					return true;
 				}
-				linex++;
+				linex+=1+3*(source[idx]=='\t');
 				idx++;
 			}
 			if(eof())return false;
@@ -200,7 +222,7 @@ public:
 			if(source[nextidx]=='.'){
 				nextidx++;
 				if(eof(nextidx)||!isdigit(source[nextidx])){
-					throw ParseError("Incomplete floating point literal at EOF");
+					throw ParseError(site(),"Incomplete floating point literal at EOF");
 				}
 				while(!eof(nextidx)&&isdigit(source[nextidx]))nextidx++;
 				if(eof(nextidx))return true;
@@ -208,11 +230,11 @@ public:
 			if(strchr("eE",source[nextidx])!=NULL){
 				nextidx++;
 				if(eof(nextidx)||strchr("+-0123456789",source[nextidx])==NULL){
-					throw ParseError("Incomplete floating point literal at EOF");
+					throw ParseError(site(),"Incomplete floating point literal at EOF");
 				}
 				if(strchr("+-",source[nextidx])!=NULL){
 					nextidx++;
-					if(eof(nextidx))throw ParseError("Incomplete floating point literal at EOF");
+					if(eof(nextidx))throw ParseError(site(),"Incomplete floating point literal at EOF");
 				}
 				while(!eof(nextidx)&&isdigit(source[nextidx]))nextidx++;
 			}
@@ -225,8 +247,9 @@ public:
 			nextidx++;
 			while(!eof(nextidx)&&source[nextidx]!='"'){
 				if(source[nextidx]=='\\')nextidx++;
+				nextidx++;
 			}
-			if(eof(nextidx))throw ParseError("Incomplete string literal at EOF");
+			if(eof(nextidx))throw ParseError(site(),"Incomplete string literal at EOF");
 			nextidx++;
 			return true;
 		}
@@ -236,23 +259,266 @@ public:
 			ttype=Token::Type::symbol;
 			nextidx++;
 			while(!eof(nextidx)){
-				if(!isSymbolPrefix(get_()))return true;
+				if(!isSymbolPrefix(get_())){
+					nextidx--;
+					return true;
+				}
 				nextidx++;
 			}
+			nextidx--;
 			if(contains(tok_symbols,get_()))return true;
-			else throw ParseError("Unknown symbol at EOF");
+			else throw ParseError(site(),"Unknown symbol at EOF");
 		}
 
-		throw ParseError("Unknown token starting at '"+source.substr(idx,5)+"'");
+		throw ParseError(site(),"Unknown token starting at '"+source.substr(idx,5)+"'");
 	}
 };
 
 
-static Expression parseExpression(Tokeniser &tokeniser){
-	;
+enum class Associativity{
+	left,
+	right,
+};
+
+struct OpInfo{
+	string name;
+	int prec; //higher is tighter-binding
+	Associativity assoc;
+};
+
+unordered_map<string,OpInfo> optable={
+	{"*", {"*", 6,Associativity::left}},
+	{"/", {"/", 6,Associativity::left}},
+	{"%", {"%", 6,Associativity::left}},
+
+	{"+", {"+", 5,Associativity::left}},
+	{"-", {"-", 5,Associativity::left}},
+
+	{"==",{"==",3,Associativity::left}},
+	{"!=",{"!=",3,Associativity::left}},
+	{">", {">", 3,Associativity::left}},
+	{"<", {"<", 3,Associativity::left}},
+	{">=",{">=",3,Associativity::left}},
+	{"<=",{"<=",3,Associativity::left}},
+};
+
+static char unhexchar(char c){
+	if(c>='0'&&c<='9')return c-'0';
+	if(c>='a'&&c<='f')return c-'a'+10;
+	if(c>='A'&&c<='F')return c-'A'+10;
+	return (char)-1;
+}
+
+static string parseString(const string &repr,Site site){
+	if(repr.size()<2||repr[0]!='"'||repr.back()!='"')throw runtime_error("String not surrounded with quotes");
+	string res;
+	res.reserve(repr.size()+3);
+	for(i64 i=1;i<(i64)repr.size()-1;i++){
+		if(repr[i]=='\\'){
+			switch(repr[i+1]){
+				case 'n': res+='\n'; i++; break;
+				case 'r': res+='\r'; i++; break;
+				case 't': res+='\t'; i++; break;
+				case '"': res+='"'; i++; break;
+				case 'x':{
+					if(i+3>=(i64)repr.size()-1)throw ParseError(site.addX(i),"Invalid hexadecimal escape");
+					char c1=unhexchar(repr[i+2]);
+					char c2=unhexchar(repr[i+3]);
+					if(c1==(char)-1||c2==(char)-1)throw ParseError(site.addX(i),"Invalid hexadecimal escape");
+					res+=(char)(16*c1+c2);
+					i+=3;
+					break;
+				}
+				default:
+					throw ParseError(site.addX(i),"Invalid hexadecimal escape");
+			}
+		} else {
+			res+=repr[i];
+		}
+	}
+	return res;
+}
+
+static Expression parseExpression(Tokeniser &tokeniser,int minprec=-1);
+static StatementList parseScope(Tokeniser &tokeniser);
+
+static vector<Expression> parseArgumentList(Tokeniser &tokeniser){
+	if(tokeniser.eof())throw ParseError(tokeniser.site(),"Expected argument list but found EOF");
+	Token tok=tokeniser.get();
+	if(tok.type!=Token::Type::symbol||tok.str!="("){
+		throw ParseError(tok.site,"Expected argument list but found '"+tok.str+"'");
+	}
+	tokeniser.advance();
+	vector<Expression> args;
+	while(true){
+		Expression expr=parseExpression(tokeniser);
+		if(tokeniser.eof()){
+			throw ParseError(tokeniser.site(),"Expected ')' or ',' after argument but found EOF");
+		}
+		tok=tokeniser.get();
+		if(tok.type!=Token::Type::symbol||(tok.str!=")"&&tok.str!=",")){
+			throw ParseError(tok.site,"Expected ')' or ',' after argument but found something else");
+		}
+		tokeniser.advance();
+		args.push_back(expr);
+		if(tok.str==")")break;
+	}
+	return args;
+}
+
+static Expression parseAtom(Tokeniser &tokeniser){
+	if(tokeniser.eof())throw ParseError(tokeniser.site(),"Expected atom but found EOF");
+	Token tok=tokeniser.get();
+	switch(tok.type){
+		case Token::Type::word:{
+			tokeniser.advance();
+			if(tokeniser.eof()){
+				if(tok.str=="if")throw ParseError(tok.site,"Expected expressions after 'if' but found EOF");
+				Expression expr=Expression(Expression::Type::call,tok.str,vector<Expression>());
+				expr.site=tok.site;
+				return expr;
+			}
+			if(tok.str=="if"){
+				Expression cond=parseExpression(tokeniser);
+				if(tokeniser.eof())throw ParseError(tokeniser.site(),"Expected 'then' but found EOF");
+				Token tok2=tokeniser.get();
+				if(tok2.type!=Token::Type::word||tok2.str!="then"){
+					throw ParseError(tok2.site,"Expected 'then' but got '"+tok2.str+"'");
+				}
+				Expression ex1=parseExpression(tokeniser);
+				if(tokeniser.eof())throw ParseError(tokeniser.site(),"Expected 'else' but found EOF");
+				tok2=tokeniser.get();
+				if(tok2.type!=Token::Type::word||tok2.str!="else"){
+					throw ParseError(tok2.site,"Expected 'else' but got '"+tok2.str+"'");
+				}
+				Expression ex2=parseExpression(tokeniser);
+
+				return Expression(Expression::Type::cond,{cond,ex1,ex2});
+			}
+
+			Token tok2=tokeniser.get();
+			if(tok2.type==Token::Type::symbol&&tok2.str=="("){
+				vector<Expression> args=parseArgumentList(tokeniser);
+				bool done=false;
+				if(tokeniser.eof())done=true;
+				else {
+					tok2=tokeniser.get();
+					if(tok2.type!=Token::Type::symbol||tok2.str!="{")done=true;
+				}
+				if(done){
+					Expression expr=Expression(Expression::Type::call,tok.str,args);
+					expr.site=tok.site;
+					return expr;
+				}
+				return Expression(Expression::Type::dive,tok.str,args,
+				                  Scope(Scope::Type::direct,parseScope(tokeniser),{}));
+			} else if(tok2.type==Token::Type::symbol&&tok2.str=="{"){
+				return Expression(Expression::Type::dive,tok.str,{},
+				                  Scope(Scope::Type::direct,parseScope(tokeniser),{}));
+			} else {
+				Expression expr=Expression(Expression::Type::call,tok.str,vector<Expression>());
+				expr.site=tok.site;
+				return expr;
+			}
+		}
+
+		case Token::Type::number:{
+			tokeniser.advance();
+			Expression expr=Expression(Expression::Type::number,strtod(tok.str.data(),nullptr));
+			expr.site=tok.site;
+			return expr;
+		}
+
+		case Token::Type::string:{
+			tokeniser.advance();
+			Expression expr=Expression(Expression::Type::string,parseString(tok.str,tok.site));
+			expr.site=tok.site;
+			return expr;
+		}
+
+		case Token::Type::symbol:{
+			if(tok.str=="("){
+				tokeniser.advance();
+				Expression expr=parseExpression(tokeniser);
+				if(tokeniser.eof())throw ParseError(tokeniser.site(),"Expected ')' but found EOF");
+				Token tok2=tokeniser.get();
+				if(tok2.type!=Token::Type::symbol||tok2.str!=")"){
+					throw ParseError(tok2.site,"Expected ')' but found something else");
+				}
+				tokeniser.advance();
+				return expr;
+			}
+			Scope::Type sctype;
+			if(tok.str=="?")sctype=Scope::Type::lazy;
+			else if(tok.str=="??")sctype=Scope::Type::function;
+			else if(tok.str!="{"){
+				throw ParseError(tok.site,"Unexpected token '"+tok.str+"' in expression atom position");
+			} else sctype=Scope::Type::direct;
+			vector<Expression> args;
+			if(sctype!=Scope::Type::direct){
+				tokeniser.advance();
+				if(tokeniser.eof()){
+					throw ParseError(tokeniser.site(),"Expected scope after '"+tok.str+"' but found EOF");
+				}
+				Token tok2=tokeniser.get();
+				if(tok2.type!=Token::Type::symbol){
+					throw ParseError(tok2.site,"Expected '(' or '{' after '"+tok.str+"'");
+				}
+				if(tok2.type==Token::Type::symbol&&tok2.str=="("){
+					args=parseArgumentList(tokeniser);
+				}
+			}
+			// DEBUG<<"args: "<<args<<endl;
+			// DEBUG<<"get(): "<<tokeniser.get().str<<endl;
+			if(tokeniser.eof())throw ParseError(tokeniser.site(),"Expected '{' to begin scope");
+			Token tok2=tokeniser.get();
+			if(tok2.type!=Token::Type::symbol||tok2.str!="{"){
+				throw ParseError(tok2.site,"Expected '{' to begin scope");
+			}
+			Scope sc(sctype,parseScope(tokeniser),args);
+			return Expression(Expression::Type::scope,sc);
+		}
+
+		case Token::Type::terminator:
+			throw ParseError(tok.site,"Expected expression atom but found statement terminator (newline or ';')");
+	}
+}
+
+static Expression parseExpression(Tokeniser &tokeniser,int minprec){
+	Expression result=parseAtom(tokeniser);
+	while(!tokeniser.eof()){
+		Token tok=tokeniser.get();
+		if(tok.type==Token::Type::terminator||
+		   (tok.type==Token::Type::symbol&&(tok.str==","||tok.str==")"))||
+		   (tok.type==Token::Type::word&&(tok.str=="then"||tok.str=="else")))break;
+		if(tok.type!=Token::Type::symbol){
+			throw ParseError(tok.site,"Expected operator in expression");
+		}
+		auto it=optable.find(tok.str);
+		if(it==optable.end()){
+			throw ParseError(tok.site,"Undefined operator '"+tok.str+"'");
+		}
+		const OpInfo &op=it->second;
+
+		if(op.prec<minprec)break;
+		tokeniser.advance();
+		i64 nextminprec;
+		switch(op.assoc){
+			case Associativity::left: nextminprec=op.prec+1; break;
+			case Associativity::right: nextminprec=op.prec; break;
+		}
+		Expression rhs=parseExpression(tokeniser,nextminprec);
+		Site oldsite=result.site;
+		result=Expression(Expression::Type::binop,op.name,{result,rhs});
+		result.site=oldsite;
+	}
+	return result;
 }
 
 static Statement parseStatement(Tokeniser &tokeniser){
+	if(tokeniser.eof()){
+		throw ParseError(tokeniser.site(),"Expected statement but found EOF");
+	}
 	Token tok=tokeniser.get();
 	switch(tok.type){
 		case Token::Type::word:{
@@ -262,32 +528,67 @@ static Statement parseStatement(Tokeniser &tokeniser){
 			if(tok2.type==Token::Type::symbol&&tok2.str==":="){
 				tokeniser=copyiser;
 				tokeniser.advance();
-				return Statement(Statement::Type::create,tok.str,parseExpression(tokeniser));
+				Statement st=Statement(Statement::Type::create,tok.str,parseExpression(tokeniser));
+				st.site=tok.site;
+				return st;
 			} else if(tok2.type==Token::Type::symbol&&tok2.str=="="){
 				tokeniser=copyiser;
 				tokeniser.advance();
-				return Statement(Statement::Type::assign,tok.str,parseExpression(tokeniser));
+				Statement st=Statement(Statement::Type::assign,tok.str,parseExpression(tokeniser));
+				st.site=tok.site;
+				return st;
 			} else {
-				return Statement(Statement::Type::expression,parseExpression(tokeniser));
+				Statement st=Statement(Statement::Type::expression,parseExpression(tokeniser));
+				st.site=tok.site;
+				return st;
 			}
 		}
 
 		case Token::Type::number:
 		case Token::Type::string:
-		case Token::Type::symbol:
-			return Statement(Statement::Type::expression,parseExpression(tokeniser));
+		case Token::Type::symbol:{
+			Statement st=Statement(Statement::Type::expression,parseExpression(tokeniser));
+			st.site=tok.site;
+			return st;
+		}
 
 		case Token::Type::terminator:
 			throw runtime_error("Unexpected terminator in parseStatement()");
 	}
 }
 
+static StatementList parseScope(Tokeniser &tokeniser){
+	if(tokeniser.eof())throw ParseError(tokeniser.site(),"Expected scope");
+	Token tok=tokeniser.get();
+	if(tok.type!=Token::Type::symbol||tok.str!="{"){
+		throw ParseError(tok.site,"Expected scope but found '"+tok.str+"'");
+	}
+	if(!tokeniser.advance())throw ParseError(tok.site,"Incomplete scope at EOF");
+	StatementList stl;
+	while(true){
+		if(tokeniser.eof())throw ParseError(tokeniser.site(),"Incomplete scope at EOF");
+		tok=tokeniser.get();
+		if(tok.type==Token::Type::terminator){
+			tokeniser.advance();
+			continue;
+		}
+		if(tok.type==Token::Type::symbol&&tok.str=="}")break;
+		stl.push_back(parseStatement(tokeniser));
+	}
+	tokeniser.advance();
+	// DEBUG<<"leaving parseScope with tokeniser at "<<tokeniser.site()<<endl;
+	return stl;
+}
+
 StatementList parse(const string &source,const string &filename){
 	Tokeniser tokeniser(source,filename);
 	if(!tokeniser.advance())return {};
 	StatementList stl;
 	while(!tokeniser.eof()){
-		if(tokeniser.get().type==Token::Type::terminator)continue;
+		if(tokeniser.get().type==Token::Type::terminator){
+			tokeniser.advance();
+			continue;
+		}
 		stl.push_back(parseStatement(tokeniser));
 	}
 	return stl;
diff --git a/parser.h b/parser.h
index 0c860d5..4cf0918 100644
--- a/parser.h
+++ b/parser.h
@@ -9,6 +9,7 @@ class ParseError : public runtime_error{
 public:
 	explicit ParseError(const string &what_arg);
 	explicit ParseError(const char *what_arg);
+	ParseError(Site site,const string &what_arg);
 };
 
 StatementList parse(const string &source,const string &filename);