Experimental Google Go backend for Idris

Motivations for this

• I felt like improving my Haskell and Idris, and learning Go
• ???

Some features/benefits

• Easy interop with Go, as well as with C via cgo
• UTF-8 support
• Callbacks from Go (into Idris) support
• With no tweaking yet, performance seems quite good -- almost as fast as C backend

Niceties/notes

• Go compiles pretty fast, which is nice when using it for a language backend
• Go has a reasonably-well-performing GC (which is continually being improved)
• Go has built-in unicode support (used by this backend)
• Go has standard lib big int support (used by this backend)
• Go has nice reflection features (used by this backend, made things pretty easy)
• No Go third-party libraries needed or used by this backend
• Most of the official Idris tests run successfully -- see the Makefile

Some code examples

• UTF-8 support, so this works and produces "βγδ" as output (the C backend doesn't yet)

module Main

greek : String
greek = "αβγδ"

main : IO ()
main = do
  putStrLn "Running Idris main"
  putStrLn $ "Greek: " ++ (strTail greek)

• Calling a Go function via the FFI

module Main

%include go "fmt"

goprint : String -> IO ()
goprint s = mkForeign (FFun "fmt.Println(%0)" [FString] FUnit) s

main : IO ()
main = do
  goprint "Hello, world!"

• Calling a C function via the FFI (via cgo)

module Main

%include go "// #include <stdio.h>"
%include go "C"

c_putchar : Char -> IO Int
c_putchar c = mkForeign (FFun "C.putchar(C.int(%0))" [FChar] FInt) c

main : IO ()
main = do

  _ <- c_putchar('B')
  _ <- c_putchar('\n')

  return ()