enso.nim: Added file operations

src/enso.nim

@@ -1,11 +1,14 @@
-import std/sugar
+import std/[options, os, sugar]
 
 # Declarations
 
 type
+  Error*    = enum OK, ERR
   FileDesc* = enum STDIN, STDOUT, STDERR
   IO*[T]    = proc(): T
 
+func fileread*(file: string): IO[Option[string]]
+func filewrite*(data: string, file: string): IO[Error]
 func flatmap*[T, U](io: IO[T], fn: T -> IO[U]): IO[U]
 func lift*(fn: proc(): void): IO[void]
 func lift*[T](fn: proc(): T): IO[T]
@@ -15,9 +18,35 @@ func readstr*(stream: FileDesc): IO[string]
 func run*[T](io: IO[T]): T
 func strput*(str: string): IO[void]
 func to_IO*[T](val: T): IO[T]
-     
+
+# Unsafe
+
+proc read_unsafe(file: string): Option[string] =
+  try:
+    let data: string = readFile(file)
+    some(data)
+  except IOError:
+    none(string)
+
+proc write_unsafe(data: string, file: string): Error =
+  try:
+    writeFile(file, data)
+    OK
+  except IOError:
+    ERR
+
 # Definitions
 
+func fileread*(file: string): IO[Option[string]] =
+  proc(): Option[string] =
+    if fileExists(file):
+      read_unsafe(file)
+    else:
+      none(string)
+
+func filewrite*(data: string, file: string): IO[Error] =
+  proc(): Error = write_unsafe(data, file)
+
 func flatmap*[T, U](io: IO[T], fn: T -> IO[U]): IO[U] = join(map(io, fn))
 
 func lift*(fn: proc(): void): IO[void] =