Added an optional prompt parameter to readline and renamed it to readLine. Added string support in toInt

src/stdlib.nim

@@ -25,6 +25,8 @@ import types/native
 import times
 import math
 import strformat
+import parseutils
+import strutils
 
 
 
@@ -47,10 +49,17 @@ proc natPrint*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
     # to nil
     return (kind: retNative.Nil, result: nil)
 
+
 proc natReadline*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
     ## Native function readline
     ## Reads a line from stdin and returns
-    ## it as a string.
+    ## it as a string, optionally writing
+    ## a given prompt to stdout
+    if len(args) > 1:
+        return (kind: retNative.Exception, result: newTypeError(&"Function 'readLine' takes 0 to 1 arguments, got {len(args)}"))
+    elif not args[0].isStr():
+        return (kind: retNative.Exception, result: newTypeError(&"The prompt must be of type 'string', not '{args[0].typeName()}'"))
+    stdout.write(args[0].toStr())
     return (kind: retNative.Object, result: stdin.readLine().asStr())
 
 
@@ -65,7 +74,7 @@ proc natClock*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
     result = (kind: retNative.Object, result: getTime().toUnixFloat().asFloat())
 
 
-proc natRound*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] = 
+proc natRound*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
     ## Rounds a floating point number to a given
     ## precision (when precision == 0, this function drops the
     ## decimal part and returns an integer). Note that when
@@ -94,22 +103,34 @@ proc natRound*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
             result = (kind: retNative.Object, result: round(args[0].toFloat(), precision).asFloat())
 
 
-proc natToInt*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] = 
-    ## Drops the decimal part of a float and returns an integer.
+proc natToInt*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
+    ## Drops the decimal part of a float and returns an integer or
+    ## converts an integer string to an actual integer object.
     ## If the value is already an integer, the same object is returned
     if args[0].isInt():
         result = (kind: retNative.Object, result: args[0])
     elif args[0].isFloat():
         result = (kind: retNative.Object, result: int(args[0].toFloat()).asInt())
+    elif args[0].isStr():
+        let s = args[0].toStr()
+        for c in s:
+            if not c.isDigit():
+                return (kind: retNative.Exception, result: newValueError("invalid argument"))
+        try:
+            var num: int
+            discard parseInt(args[0].toStr(), num)
+            result = (kind: retNative.Object, result: num.asInt())
+        except ValueError:
+            result = (kind: retNative.Exception, result: newValueError("invalid argument"))
     else:
-        result = (kind: retNative.Exception, result: newTypeError(&"input must be of type 'int' or 'float', not '{args[0].typeName()}'"))
+        result = (kind: retNative.Exception, result: newTypeError(&"input must be of type 'int', 'float' or 'string', not '{args[0].typeName()}'"))
 
 
-proc natType*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] = 
+proc natType*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
     ## Returns the type of a given object as a string
     result = (kind: retNative.Object, result: args[0].typeName().asStr())
 
 
-proc natToString*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] = 
+proc natToString*(args: seq[ptr Obj]): tuple[kind: retNative, result: ptr Obj] =
     ## Returns the string representation of an object
     result = (kind: retNative.Object, result: args[0].stringify().asStr())

src/types/exception.nim

@@ -59,5 +59,11 @@ proc newTypeError*(message: string): ptr JAPLException =
     result.message = message
 
 
+proc newValueError*(message: string): ptr JAPLException =
+    result = allocateObj(JAPLException, ObjectType.Exception)
+    result.errName = "ValueError"
+    result.message = message
+
+
 proc stringify*(self: ptr JAPLException): string =
-    result = &"{self.errName}: {self.message}"
+    result = &"{self.errName}: {self.message}"

src/vm.nim

@@ -720,7 +720,7 @@ proc initStdlib*(vm: VM) =
         vm.defineGlobal("toInt", newNative("toInt", natToInt, 1))
         vm.defineGlobal("toString", newNative("toString", natToString, 1))
         vm.defineGlobal("type", newNative("type", natType, 1))
-        vm.defineGlobal("readline", newNative("readline", natReadline, 0))
+        vm.defineGlobal("readLine", newNative("readLine", natReadline, -1))
     when DEBUG_TRACE_VM and SKIP_STDLIB_INIT:
         echo "DEBUG - VM: Skipping stdlib initialization"
 

tests/japl/for_with_function.jpl

@@ -3,8 +3,7 @@ var y = 0; //a global to keep track of state
 //does not need closures for this to work yet
 
 fun next(x) {
-    if (x == 10)
-    {
+    if (x == 0) {
         y = y + 1;
         x = 0;
     }
@@ -13,8 +12,7 @@ fun next(x) {
     return x+y+1;
 }
 
-var i = 0;
-for (; i != -1; i = next(i))
+for (var i = 0; i != -1; i = next(i))
     print(i);
 // before using next
 //stdout:0

tests/japl/inputtest.jpl

@@ -1,3 +1,3 @@
 //stdin:Hello world!
-print(readline());
+print(readLine());
 //stdout:Hello world!