enso: Init repo

src/enso.nim

@@ -0,0 +1,59 @@
+import std/sugar
+
+# Declarations
+
+type FileDesc* = enum STDIN, STDOUT, STDERR
+type IO*[T]    = proc(): T
+
+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]
+func join*[T](io: IO[IO[T]]): IO[T]
+func map*[T, U](io: IO[seq[T]], fn: T -> U): IO[seq[U]]
+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]
+     
+# Definitions
+
+func flatmap*[T, U](io: IO[T], fn: T -> IO[U]): IO[U] = join(io.map(fn))
+
+func lift*(fn: proc(): void): IO[void] =
+  proc(): void = fn()
+    
+func lift*[T](fn: proc(): T): IO[T] =
+  proc(): T = fn()
+
+func join*[T](io: IO[IO[T]]): IO[T] = io.map(run)
+  
+func map*[T, U](io: IO[seq[T]], fn: T -> U): IO[seq[U]] =
+  proc(): seq[U] =
+    let list: seq[T] = io()
+
+    if list.len == 0:
+      @[]
+    else:
+      let
+        head: T          = list[0]
+        tail: seq[T]     = list[1..^1]
+        new:  IO[seq[T]] = to_IO tail
+
+      @[fn(head)] & run new.map(fn)
+
+func readstr*(stream: FileDesc): IO[string] =
+  case stream:
+    of STDIN:
+      lift proc(): string = readLine(stdin)
+    of STDOUT:
+      lift proc(): string = readLine(stdout)
+    of STDERR:
+      lift proc(): string = readLine(stderr)
+
+func run*[T](io: IO[T]): T = io()
+
+func strput*(str: string): IO[void] =
+  proc(): void = echo str
+
+func to_IO*[T](val: T): IO[T] =
+  proc(): T = val