diff --git a/grammar/culebra.peg b/grammar/culebra.peg
index 3819583..861e40b 100644
--- a/grammar/culebra.peg
+++ b/grammar/culebra.peg
@@ -1,78 +1,86 @@
 
-    PROGRAM                  <-  _ STATEMENTS
-    STATEMENTS               <-  (STATEMENT (';' _)?)*
-    STATEMENT                <-  DEBUGGER / RETURN / EXPRESSION
+PROGRAM                  <-  _ STATEMENTS _
+STATEMENTS               <-  (STATEMENT (_sp_ (';' / _nl_) (_ STATEMENT)?)*)?
+STATEMENT                <-  DEBUGGER / RETURN / EXPRESSION
 
-    DEBUGGER                 <-  debugger
-    RETURN                   <-  return End _ / return EXPRESSION
+DEBUGGER                 <-  debugger
+RETURN                   <-  return (_sp_ !_nl_ EXPRESSION)?
 
-    EXPRESSION               <-  ASSIGNMENT / LOGICAL_OR
+EXPRESSION               <-  ASSIGNMENT / LOGICAL_OR
 
-    ASSIGNMENT               <-  MUTABLE PRIMARY (ARGUMENTS / INDEX / DOT)* '=' _ EXPRESSION
+ASSIGNMENT               <-  MUTABLE _ PRIMARY (_ (ARGUMENTS / INDEX / DOT))* _ '=' _ EXPRESSION
 
-    LOGICAL_OR               <-  LOGICAL_AND ('||' _ LOGICAL_AND)*
-    LOGICAL_AND              <-  CONDITION ('&&' _  CONDITION)*
-    CONDITION                <-  ADDITIVE (CONDITION_OPERATOR ADDITIVE)*
-    ADDITIVE                 <-  UNARY_PLUS (ADDITIVE_OPERATOR UNARY_PLUS)*
-    UNARY_PLUS               <-  UNARY_PLUS_OPERATOR? UNARY_MINUS
-    UNARY_MINUS              <-  UNARY_MINUS_OPERATOR? UNARY_NOT
-    UNARY_NOT                <-  UNARY_NOT_OPERATOR? MULTIPLICATIVE
-    MULTIPLICATIVE           <-  CALL (MULTIPLICATIVE_OPERATOR CALL)*
+LOGICAL_OR               <-  LOGICAL_AND (_ '||' _ LOGICAL_AND)*
+LOGICAL_AND              <-  CONDITION (_ '&&' _  CONDITION)*
+CONDITION                <-  ADDITIVE (_ CONDITION_OPERATOR _ ADDITIVE)*
+ADDITIVE                 <-  UNARY_PLUS (_ ADDITIVE_OPERATOR _ UNARY_PLUS)*
+UNARY_PLUS               <-  UNARY_PLUS_OPERATOR? UNARY_MINUS
+UNARY_MINUS              <-  UNARY_MINUS_OPERATOR? UNARY_NOT
+UNARY_NOT                <-  UNARY_NOT_OPERATOR? MULTIPLICATIVE
+MULTIPLICATIVE           <-  CALL (_ MULTIPLICATIVE_OPERATOR _ CALL)*
 
-    CALL                     <-  PRIMARY (ARGUMENTS / INDEX / DOT)*
-    ARGUMENTS                <-  '(' _ (EXPRESSION (',' _ EXPRESSION)*)? ')' _
-    INDEX                    <-  '[' _ EXPRESSION ']' _
-    DOT                      <-  '.' _ IDENTIFIER
+CALL                     <-  PRIMARY (_ (ARGUMENTS / INDEX / DOT))*
+ARGUMENTS                <-  '(' _ (EXPRESSION (_ ',' _ EXPRESSION)*)? _ ')'
+INDEX                    <-  '[' _ EXPRESSION _ ']'
+DOT                      <-  '.' _ IDENTIFIER
 
-    WHILE                    <-  while EXPRESSION BLOCK
-    IF                       <-  if EXPRESSION BLOCK (else if EXPRESSION BLOCK)* (else BLOCK)?
+WHILE                    <-  while _ EXPRESSION _ BLOCK
+IF                       <-  if _ EXPRESSION _ BLOCK (_ else _ if _ EXPRESSION _ BLOCK)* (_ else _ BLOCK)?
 
-    PRIMARY                  <-  WHILE / IF / FUNCTION / OBJECT / ARRAY / UNDEFINED / BOOLEAN / NUMBER / IDENTIFIER / STRING / INTERPOLATED_STRING / '(' _ EXPRESSION ')' _
+PRIMARY                  <-  WHILE / IF / FUNCTION / OBJECT / ARRAY / UNDEFINED / BOOLEAN / NUMBER / IDENTIFIER / STRING / INTERPOLATED_STRING / '(' _ EXPRESSION _ ')'
 
-    FUNCTION                 <-  fn PARAMETERS BLOCK
-    PARAMETERS               <-  '(' _ (PARAMETER (',' _ PARAMETER)*)? ')' _
-    PARAMETER                <-  MUTABLE IDENTIFIER
+FUNCTION                 <-  fn _ PARAMETERS _ BLOCK
+PARAMETERS               <-  '(' _ (PARAMETER (_ ',' _ PARAMETER)*)? _ ')'
+PARAMETER                <-  MUTABLE _ IDENTIFIER
 
-    BLOCK                    <-  '{' _ STATEMENTS '}' _
+BLOCK                    <-  '{' _ STATEMENTS _ '}'
 
-    CONDITION_OPERATOR       <-  < ('==' / '!=' / '<=' / '<' / '>=' / '>') > _
-    ADDITIVE_OPERATOR        <-  < [-+] > _
-    UNARY_PLUS_OPERATOR      <-  < '+' > _
-    UNARY_MINUS_OPERATOR     <-  < '-' > _
-    UNARY_NOT_OPERATOR       <-  < '!' > _
-    MULTIPLICATIVE_OPERATOR  <-  < [*/%] > _
+CONDITION_OPERATOR       <-  '==' / '!=' / '<=' / '<' / '>=' / '>'
+ADDITIVE_OPERATOR        <-  [-+]
+UNARY_PLUS_OPERATOR      <-  '+'
+UNARY_MINUS_OPERATOR     <-  '-'
+UNARY_NOT_OPERATOR       <-  '!'
+MULTIPLICATIVE_OPERATOR  <-  [*/%]
 
-    IDENTIFIER               <-  < IdentInitChar IdentChar* > _
+MUTABLE                  <-  < ('mut' _wd_)? >
 
-    OBJECT                   <-  '{' _ (OBJECT_PROPERTY (',' _ OBJECT_PROPERTY)*)? '}' _
-    OBJECT_PROPERTY          <-  MUTABLE IDENTIFIER ':' _ EXPRESSION
+IDENTIFIER               <-  < IdentInitChar IdentChar* >
 
-    ARRAY                    <-  '[' _ (EXPRESSION (',' _ EXPRESSION)*)? ']' _
+OBJECT                   <-  '{' _ (OBJECT_PROPERTY (_ ',' _ OBJECT_PROPERTY)*)? _ '}'
+OBJECT_PROPERTY          <-  MUTABLE _ IDENTIFIER _ ':' _ EXPRESSION
 
-    UNDEFINED                <-  < 'undefined' > __
-    BOOLEAN                  <-  < ('true' / 'false') > __
-    MUTABLE                  <-  (< 'mut' > __)?
+ARRAY                    <-  '[' _ (EXPRESSION (',' _ EXPRESSION)*)? ']'
 
-    ~debugger                <-  'debugger' __
-    ~return                  <-  'return' !IdentInitChar Space*
-    ~while                   <-  'while' __
-    ~if                      <-  'if' __
-    ~else                    <-  'else' __
-    ~fn                      <-  'fn' __
+UNDEFINED                <-  < 'undefined' _wd_ >
+BOOLEAN                  <-  < ('true' / 'false')  _wd_ >
 
-    NUMBER                   <-  < [0-9]+ > _
-    STRING                   <-  ['] < (!['] .)* > ['] _
+NUMBER                   <-  < [0-9]+ >
+STRING                   <-  ['] < (!['] .)* > [']
 
-    INTERPOLATED_STRING      <-  '"' ('{' _ EXPRESSION '}' / INTERPOLATED_CONTENT)* '"' _
-    INTERPOLATED_CONTENT     <-  (!["{] .) (!["{] .)*
+INTERPOLATED_STRING      <-  '"' ('{' _ EXPRESSION _ '}' / INTERPOLATED_CONTENT)* '"'
+INTERPOLATED_CONTENT     <-  (!["{] .) (!["{] .)*
 
-    ~_                       <-  (Space / End)*
-    __                       <-  !IdentInitChar (Space / End)*
-    ~Space                   <-  ' ' / '\t' / Comment
-    ~End                     <-  EndOfLine / EndOfFile
-    Comment                  <-  '/*' (!'*/' .)* '*/' /  ('#' / '//') (!End .)* &End
-    EndOfLine                <-  '\r\n' / '\n' / '\r'
-    EndOfFile                <-  !.
-    IdentInitChar            <-  [a-zA-Z_]
-    IdentChar                <-  [a-zA-Z0-9_]
+~debugger                <- 'debugger' _wd_
+~while                   <- 'while' _wd_
+~if                      <- 'if' _wd_
+~else                    <- 'else' _wd_
+~fn                      <- 'fn' _wd_
+~return                  <- 'return' _wd_
+
+~_                       <-  (WhiteSpace / End)*
+~_sp_                    <-  SpaceChar*
+~_nl_                    <-  LineComment? End
+~_wd_                    <-  !IdentInitChar
+
+WhiteSpace               <-  SpaceChar / Comment
+End                      <-  EndOfLine / EndOfFile
+Comment                  <-  BlockComment / LineComment
+
+SpaceChar                <-  ' ' / '\t'
+EndOfLine                <-  '\r\n' / '\n' / '\r'
+EndOfFile                <-  !.
+IdentInitChar            <-  [a-zA-Z_]
+IdentChar                <-  [a-zA-Z0-9_]
+BlockComment             <-  '/*' (!'*/' .)* '*/'
+LineComment              <-  ('#' / '//') (!End .)* &End