[Agda] Perplexed by compile behavior

Chris Moline blackredtree at gmail.com
Fri Aug 23 11:03:51 CEST 2013

I've been trying to agda but I'm stumped by compiling a simple hello world

In emacs the file loads without error but when I try to compile it with the
command line program I get this:

Compiling Learn in /home/cmo/src/agda/Learn/Learn.agdai to

The type of main should be .IO.Primitive.IO A, for some A. The
given type is .IO.IO .Data.Unit.[~/src/agda/Learn] $

My hello world application looks like this:

module Learn where

open import Data.String
open import Data.Unit
open import IO

main : IO ⊤
main = putStrLn "hello"

The script that I'm using to compile the file is:

agda -c \
     -i "." \
     -i ~/.cabal/lib/Agda- \
     -i ~/src/agda/lib-0.7/src \

My ghc version is 7.6.3 and agda is version

I'm really perplexed by the behavior of the agda programs. In the beginning
the same program I gave above would end with a parse error at eof. Then
that magically stopped. Then the compile would break without giving an
error message. It turned out that I gave main the type : String -> IO T but
still no error message? . Now finally I have the above error. I realize
that agda is in its early stages so it's no big deal, I just have no idea
why a simple program gives so much trouble.

Anyways I hope someone will give me advice as to what I'm doing wrong.
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