`do' keyword in the grammar for lambda blocks

compiler/ast.nim

@@ -93,6 +93,7 @@ type
     nkElifExpr,
     nkElseExpr,
     nkLambda,             # lambda expression
+    nkDo,                 # lambda block appering as trailing proc param
     nkAccQuoted,          # `a` as a node
 
     nkTableConstr,        # a table constructor {expr: expr}
@@ -644,6 +645,8 @@ proc copyTree*(src: PNode): PNode
 const nkCallKinds* = {nkCall, nkInfix, nkPrefix, nkPostfix, nkCommand,
                       nkCallStrLit}
 
+const nkLambdaKinds* = {nkLambda, nkDo}
+
 proc isCallExpr*(n: PNode): bool =
   result = n.kind in nkCallKinds
 

compiler/ccgexprs.nim

@@ -7,6 +7,8 @@
 #    distribution, for details about the copyright.
 #
 
+# included from cgen.nim
+
 proc lenField: PRope {.inline.} = 
   result = toRope(if gCmd != cmdCompileToCpp: "Sup.len" else: "len")
 
@@ -1723,7 +1725,7 @@ proc expr(p: BProc, e: PNode, d: var TLoc) =
   of nkChckRange: genRangeChck(p, e, d, "chckRange")
   of nkStringToCString: convStrToCStr(p, e, d)
   of nkCStringToString: convCStrToStr(p, e, d)
-  of nkLambda:
+  of nkLambdaKinds:
     var sym = e.sons[namePos].sym
     genProc(p.module, sym)
     if sym.loc.r == nil or sym.loc.t == nil:

compiler/evals.nim

@@ -1246,7 +1246,7 @@ proc evalAux(c: PEvalContext, n: PNode, flags: TEvalFlags): PNode =
   of nkPragmaBlock:
     result = evalAux(c, n.sons[1], flags)
   of nkIdentDefs, nkCast, nkYieldStmt, nkAsmStmt, nkForStmt, nkPragmaExpr, 
-     nkLambda, nkContinueStmt, nkIdent: 
+     nkLambdaKinds, nkContinueStmt, nkIdent: 
     result = raiseCannotEval(c, n.info)
   of nkRefTy:
     result = evalAux(c, n.sons[0], flags)

compiler/lambdalifting.nim

@@ -8,11 +8,12 @@
 #
 
 # This include file implements lambda lifting for the transformator.
+# included from transf.nim
 
 const
   declarativeDefs = {nkProcDef, nkMethodDef, nkIteratorDef,
      nkConverterDef}
-  procDefs = {nkLambda} + declarativeDefs
+  procDefs = nkLambdaKinds + declarativeDefs
 
 proc indirectAccess(a, b: PSym, info: TLineInfo): PNode = 
   # returns a[].b as a node
@@ -169,7 +170,7 @@ proc createEnvStmt(c: PTransf, varList: TCapture, env: PSym): PTransNode =
     IdNodeTablePut(c.transCon.mapping, v, fieldAccess)
   
 proc transformProcFin(c: PTransf, n: PNode, s: PSym): PTransNode =
-  if n.kind == nkLambda:
+  if n.kind in nkLambdaKinds:
     # for lambdas we transformed 'n.sons[bodyPos]', but not 'ast.n[bodyPos]'!
     s.ast.sons[bodyPos] = n.sons[bodyPos]
   else:

compiler/lexer.nim

@@ -33,8 +33,9 @@ type
     tkSymbol, # keywords:
     tkAddr, tkAnd, tkAs, tkAsm, tkAtomic, 
     tkBind, tkBlock, tkBreak, tkCase, tkCast, 
-    tkConst, tkContinue, tkConverter, tkDiscard, tkDistinct, tkDiv, tkElif, 
+    tkConst, tkContinue, tkConverter, tkDiscard, tkDistinct, tkDiv, tkDo,
-    tkElse, tkEnd, tkEnum, tkExcept, tkExport, tkFinally, tkFor, tkFrom,
+    tkElif, tkElse, tkEnd, tkEnum, tkExcept, tkExport,
+    tkFinally, tkFor, tkFrom,
     tkGeneric, tkIf, tkImport, tkIn, tkInclude, tkIs, tkIsnot, tkIterator,
     tkLambda, tkLet,
     tkMacro, tkMethod, tkMod, tkNil, tkNot, tkNotin, tkObject, tkOf, tkOr, 
@@ -48,10 +49,12 @@ type
     tkBracketDotLe, tkBracketDotRi, # [. and  .]
     tkCurlyDotLe, tkCurlyDotRi, # {.  and  .}
     tkParDotLe, tkParDotRi,   # (. and .)
-    tkComma, tkSemiColon, tkColon, tkColonColon, tkEquals, tkDot, tkDotDot, 
+    tkComma, tkSemiColon,
+    tkColon, tkColonColon, tkEquals, tkLeArrow, tkRiArrow, tkDot, tkDotDot,
     tkOpr, tkComment, tkAccent, tkInd, tkSad, 
     tkDed, # pseudo token types used by the source renderers:
-    tkSpaces, tkInfixOpr, tkPrefixOpr, tkPostfixOpr
+    tkSpaces, tkInfixOpr, tkPrefixOpr, tkPostfixOpr,
+    
   TTokTypes* = set[TTokType]
 
 const 
@@ -61,8 +64,8 @@ const
     "tkSymbol",
     "addr", "and", "as", "asm", "atomic", 
     "bind", "block", "break", "case", "cast", 
-    "const", "continue", "converter", "discard", "distinct", "div", "elif", 
+    "const", "continue", "converter", "discard", "distinct", "div", "do",
-    "else", "end", "enum", "except", "export",
+    "elif", "else", "end", "enum", "except", "export",
     "finally", "for", "from", "generic", "if", 
     "import", "in", "include", "is", "isnot", "iterator",
     "lambda", "let", 
@@ -73,9 +76,10 @@ const
     "tkIntLit", "tkInt8Lit", "tkInt16Lit", "tkInt32Lit", "tkInt64Lit", 
     "tkFloatLit", "tkFloat32Lit", "tkFloat64Lit", "tkStrLit", "tkRStrLit", 
     "tkTripleStrLit", "tkGStrLit", "tkGTripleStrLit", "tkCharLit", "(", 
-    ")", "[", "]", "{", "}", "[.", ".]", "{.", ".}", "(.", ".)", ",", ";", 
+    ")", "[", "]", "{", "}", "[.", ".]", "{.", ".}", "(.", ".)",
-    ":", "::",
+    ",", ";",
-    "=", ".", "..", "tkOpr", "tkComment", "`", "[new indentation]", 
+    ":", "::", "=", "<-", "->", ".", "..",
+    "tkOpr", "tkComment", "`", "[new indentation]", 
     "[same indentation]", "[dedentation]", "tkSpaces", "tkInfixOpr", 
     "tkPrefixOpr", "tkPostfixOpr"]
 

compiler/parser.nim

@@ -146,7 +146,8 @@ proc newIdentNodeP(ident: PIdent, p: TParser): PNode =
 proc parseExpr(p: var TParser): PNode
 proc parseStmt(p: var TParser): PNode
 proc parseTypeDesc(p: var TParser): PNode
-proc parseParamList(p: var TParser): PNode
+proc parseDoBlocks(p: var TParser, call: PNode)
+proc parseParamList(p: var TParser, resTypeTok = tkColon): PNode
 
 proc IsLeftAssociative(tok: TToken): bool {.inline.} =
   result = tok.tokType != tkOpr or tok.ident.s[0] != '^'
@@ -466,6 +467,7 @@ proc primary(p: var TParser): PNode =
       result = newNodeP(nkCall, p)
       addSon(result, a)
       exprColonEqExprListAux(p, nkExprEqExpr, tkParRi, tkEquals, result)
+      parseDoBlocks(p, result)
     of tkDot:
       result = newDotExpr(p, result)
       result = parseGStrLit(p, result)
@@ -599,7 +601,7 @@ proc parseTuple(p: var TParser): PNode =
   optPar(p)
   eat(p, tkBracketRi)
 
-proc parseParamList(p: var TParser): PNode = 
+proc parseParamList(p: var TParser, resTypeTok = tkColon): PNode = 
   var a: PNode
   result = newNodeP(nkFormalParams, p)
   addSon(result, ast.emptyNode) # return type
@@ -621,11 +623,33 @@ proc parseParamList(p: var TParser): PNode =
       optInd(p, a)
     optPar(p)
     eat(p, tkParRi)
-  if p.tok.tokType == tkColon: 
+  if p.tok.tokType == resTypeTok:
     getTok(p)
     optInd(p, result)
     result.sons[0] = parseTypeDesc(p)
 
+proc optPragmas(p: var TParser): PNode =
+  if p.tok.tokType == tkCurlyDotLe: result = parsePragma(p)
+  else: result = ast.emptyNode
+
+proc parseDoBlock(p: var TParser): PNode =
+  var info = parLineInfo(p)
+  getTok(p)
+  var params = parseParamList(p, tkRiArrow)
+  var pragmas = optPragmas(p)
+  eat(p, tkColon)
+  result = newNodeI(nkDo, info)
+  addSon(result, ast.emptyNode)       # no name part
+  addSon(result, ast.emptyNode)       # no generic parameters
+  addSon(result, params)
+  addSon(result, pragmas)
+  skipComment(p, result)
+  addSon(result, parseStmt(p))
+
+proc parseDoBlocks(p: var TParser, call: PNode) =
+  while p.tok.tokType == tkDo:
+    addSon(call, parseDoBlock(p))
+    
 proc parseProcExpr(p: var TParser, isExpr: bool): PNode = 
   # either a proc type or a anonymous proc
   var 
@@ -634,8 +658,7 @@ proc parseProcExpr(p: var TParser, isExpr: bool): PNode =
   info = parLineInfo(p)
   getTok(p)
   params = parseParamList(p)
-  if p.tok.tokType == tkCurlyDotLe: pragmas = parsePragma(p)
+  pragmas = optPragmas(p)
-  else: pragmas = ast.emptyNode
   if (p.tok.tokType == tkEquals) and isExpr: 
     result = newNodeI(nkLambda, info)
     addSon(result, ast.emptyNode)       # no name part
@@ -709,6 +732,9 @@ proc parseExprStmt(p: var TParser): PNode =
       if p.tok.tokType != tkComma: break 
       getTok(p)
       optInd(p, a)
+    if p.tok.tokType == tkDo:
+      parseDoBlocks(p, result)
+      return    
     if sonsLen(result) <= 1: result = a
     else: a = result
     if p.tok.tokType == tkColon:

compiler/renderer.nim

@@ -348,7 +348,7 @@ proc lsub(n: PNode): int =
   of nkBind: result = lsons(n) + len("bind_")
   of nkBindStmt: result = lcomma(n) + len("bind_")
   of nkCheckedFieldExpr: result = lsub(n.sons[0])
-  of nkLambda: result = lsons(n) + len("lambda__=_")
+  of nkLambda, nkDo: result = lsons(n) + len("lambda__=_") # XXX: render nkDo
   of nkConstDef, nkIdentDefs: 
     result = lcomma(n, 0, - 3)
     var L = sonsLen(n)
@@ -785,7 +785,7 @@ proc gsub(g: var TSrcGen, n: PNode, c: TContext) =
     gsub(g, n.sons[0])
   of nkCheckedFieldExpr, nkHiddenAddr, nkHiddenDeref: 
     gsub(g, n.sons[0])
-  of nkLambda: 
+  of nkLambda, nkDo: # XXX: nkDo is rendered as regular lambda
     assert(n.sons[genericParamsPos].kind == nkEmpty)
     putWithSpace(g, tkLambda, "lambda")
     gsub(g, n.sons[paramsPos])

compiler/semexprs.nim

@@ -1279,7 +1279,7 @@ proc semExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode =
     of paSingle: result = semExpr(c, n.sons[0], flags)
   of nkCurly: result = semSetConstr(c, n)
   of nkBracket: result = semArrayConstr(c, n)
-  of nkLambda: result = semLambda(c, n)
+  of nkLambdaKinds: result = semLambda(c, n)
   of nkDerefExpr: result = semDeref(c, n)
   of nkAddr: 
     result = n

compiler/semgnrc.nim

@@ -244,9 +244,9 @@ proc semGenericStmt(c: PContext, n: PNode,
       for j in countup(0, L-3): 
         addPrelimDecl(c, newSymS(skUnknown, getIdentNode(a.sons[j]), c))
   of nkProcDef, nkMethodDef, nkConverterDef, nkMacroDef, nkTemplateDef, 
-     nkIteratorDef, nkLambda: 
+     nkIteratorDef, nkLambdaKinds: 
     checkSonsLen(n, bodyPos + 1)
-    if n.kind != nkLambda:
+    if n.kind notin nkLambdaKinds:
       addPrelimDecl(c, newSymS(skUnknown, getIdentNode(n.sons[0]), c))
     openScope(c.tab)
     n.sons[genericParamsPos] = semGenericStmt(c, n.sons[genericParamsPos], 

compiler/semthreads.nim

@@ -360,7 +360,7 @@ proc analyse(c: PProcCtx, n: PNode): TThreadOwner =
     if n.sons[0].kind != nkEmpty: result = analyse(c, n.sons[0])
     else: result = toVoid
   of nkAsmStmt, nkPragma, nkIteratorDef, nkProcDef, nkMethodDef,
-     nkConverterDef, nkMacroDef, nkTemplateDef, nkLambda: 
+     nkConverterDef, nkMacroDef, nkTemplateDef, nkLambdaKinds: 
       result = toVoid
   of nkExprColonExpr:
     result = analyse(c, n.sons[1])

compiler/wordrecg.nim

@@ -24,15 +24,17 @@ type
     
     wAddr, wAnd, wAs, wAsm, wAtomic, 
     wBind, wBlock, wBreak, wCase, wCast, wConst, 
-    wContinue, wConverter, wDiscard, wDistinct, wDiv, wElif, wElse, wEnd, wEnum, 
+    wContinue, wConverter, wDiscard, wDistinct, wDiv, wDo, 
-    wExcept, wExport, wFinally, wFor, wFrom, wGeneric, wIf, wImport, wIn, 
+    wElif, wElse, wEnd, wEnum, wExcept, wExport,
+    wFinally, wFor, wFrom, wGeneric, wIf, wImport, wIn, 
     wInclude, wIs, wIsnot, wIterator, wLambda, wLet,
     wMacro, wMethod, wMod, wNil, 
     wNot, wNotin, wObject, wOf, wOr, wOut, wProc, wPtr, wRaise, wRef, wReturn, 
     wShl, wShr, wTemplate, wTry, wTuple, wType, wVar, wWhen, wWhile, wWith, 
     wWithout, wXor, wYield,
     
-    wColon, wColonColon, wEquals, wDot, wDotDot, wStar, wMinus, 
+    wColon, wColonColon, wEquals, wLeArraw, wRiArrow, wDot, wDotDot,
+    wStar, wMinus,
     wMagic, wThread, wFinal, wProfiler, wObjChecks,
     wImportCpp, wImportObjC,
     wImportCompilerProc,
@@ -66,8 +68,9 @@ const
     
     "addr", "and", "as", "asm", "atomic", 
     "bind", "block", "break", "case", "cast", 
-    "const", "continue", "converter", "discard", "distinct", "div", "elif", 
+    "const", "continue", "converter",
-    "else", "end", "enum", "except", "export", 
+    "discard", "distinct", "div", "do",
+    "elif", "else", "end", "enum", "except", "export", 
     "finally", "for", "from", "generic", "if", 
     "import", "in", "include", "is", "isnot", "iterator",
     "lambda", "let",
@@ -76,7 +79,8 @@ const
     "try", "tuple", "type", "var", "when", "while", "with", "without", "xor",
     "yield",
 
-    ":", "::", "=", ".", "..", "*", "-",
+    ":", "::", "=", "<-", "->", ".", "..",
+    "*", "-",
     "magic", "thread", "final", "profiler", "objchecks", 
     
     "importcpp", "importobjc",

doc/keywords.txt

@@ -1,9 +1,10 @@
 addr and as asm atomic
 bind block break
 case cast const continue converter
-discard distinct div
+discard distinct div do
 elif else end enum except export
-finally for from generic
+finally for from
+generic
 if import in include is isnot iterator
 lambda let
 macro method mod

lib/core/macros.nim

@@ -25,7 +25,7 @@ type
     nnkPrefix, nnkPostfix, nnkPar, nnkCurly, nnkCurlyExpr,
     nnkBracket, nnkBracketExpr, nnkPragmaExpr, nnkRange, 
     nnkDotExpr, nnkCheckedFieldExpr, nnkDerefExpr, nnkIfExpr, 
-    nnkElifExpr, nnkElseExpr, nnkLambda, nnkAccQuoted, 
+    nnkElifExpr, nnkElseExpr, nnkLambda, nnkDo, nnkAccQuoted, 
     nnkTableConstr, nnkBind, nnkSymChoice, nnkHiddenStdConv, 
     nnkHiddenSubConv, nnkHiddenCallConv, nnkConv, nnkCast, 
     nnkAddr, nnkHiddenAddr, nnkHiddenDeref, nnkObjDownConv, 

tests/run/tclosure.nim

@@ -12,6 +12,10 @@ proc foldr(n: openarray[int], fn: proc (x, y: int): int {.closure}): int =
   for i in 0..n.len-1:
     result = fn(result, n[i])
 
+proc each(n: openarray[int], fn: proc(x: int) {.closure.}) =
+  for i in 0..n.len-1:
+    fn(n[i])
+
 var
   myData: array[0..4, int] = [0, 1, 2, 3, 4]
 
@@ -24,8 +28,10 @@ proc testA() =
                 inc(p))
 
 testA()
-for x in items(myData):
+
+myData.each do (x: int):
   write(stout, x)
+
 #OUT 2 4 6 8 10