define generalised string concatination operator

examples/hello-world/src/main.lm

@@ -1,4 +1,4 @@
 use std:io
 
 fn main =
-  io:println ("Hello" <++> " " <++> "World!")
+  io:println ("Hello" <> " " <> "World!")

examples/maybe-implementation/src/main.lm

@@ -26,7 +26,7 @@ impl ToString for Maybe a
   fn show m as self -> string =
     match m
     | Nothing -> "Nothing"
-    | Just a  -> "Just " <++> show a
+    | Just a  -> "Just " <> show a
 
 fn main =
   Just 5

examples/modules/src/main.lm

@@ -3,8 +3,8 @@ use other_dir  [world] // using a directory will refer to the `lib.lm` file
 use other_dir:file [Color [..], Direction [Right, Down]]
 
 fn main =
-  do file:print (hello <++> world)
-   then file:print (other_file:hello <++> project:other_dir:world)
+  do file:print (hello <> world)
+   then file:print (other_file:hello <> project:other_dir:world)
 
 fn allowed as (Color, Direction) = (Green, Down)
 

examples/tuples/src/main.lm

@@ -5,4 +5,4 @@ fn main =
     print_user user
 
 fn print_user (name, age) as (string, int) -> () =
-  io:println (name <++> " " <++> show age)
+  io:println (name <> " " <> show age)

luminapath/std/io/lib.lm

@@ -18,7 +18,7 @@ pub fn print str as s -> () =
 @[platform "linux"]
 when s can ToString
 pub fn println str as s -> () =
-  let {ptr, len} = (show str <++> "\n") . toByteVec in
+  let {ptr, len} = (str <> "\n") . toByteVec in
     do libc:write stdout ptr (len as int)
     then ()
 

luminapath/std/list/lib.lm

@@ -162,13 +162,13 @@ pub fn split_at at list as uint, List a -> (List a, List a) =
 when a can ToString
 impl ToString for [a]
   fn show list as [a] -> string =
-    "[" <++> show_ list
+    "[" <> show_ list
   where
     fn show_ list as [a] -> string = 
       match list
       | [] -> "]"
-      | [last] -> show last <++> "]"
-      | [x : xs] -> show x <++> ", " <++> show_ xs
+      | [last] -> show last <> "]"
+      | [x : xs] -> show x <> ", " <> show_ xs
 
 
 // TODO: Considder splitting equality out from Compare

luminapath/std/list/slice.lm

@@ -75,12 +75,12 @@ pub fn to_list slice as Slice a -> List a =
 when a can ToString
 impl ToString for Slice a
   fn show slice as self -> string =
-    "[" <++> show_ slice
+    "[" <> show_ slice
     where
       fn show_ slice as Slice a -> string = 
         match split slice
         | Nothing -> "]"
         | Just (x, xs) ->
           if xs.len == 0
-            then show x <++> "]"
-            else show x <++> ", " <++> show_ xs
+            then show x <> "]"
+            else show x <> ", " <> show_ xs

luminapath/std/list/vec.lm

@@ -3,7 +3,7 @@ use std:list [Listable]
 use std:list:slice [Slice]
 use std:math [Compare [>=]]
 use std:io [crash]
-use std:string [<++>]
+use std:string [<>]
 
 // An immutable heap-allocated array
 pub type Vec a {
@@ -37,7 +37,7 @@ pub fn unsafe_set i v {ptr, len} as uint, a, Vec a -> () =
 
 pub fn from_range (start, end) f as (uint, uint), fn(uint -> a) -> Vec a =
   if start > end then
-    crash ("error: from_range end larger than start " <++> show end <++> " > " <++> show start)
+    crash ("error: from_range end larger than start " <> end <> " > " <> start)
   else
   let count = (end - start) in 
   let vec = capacity count in

luminapath/std/math/lib.lm

@@ -1,4 +1,5 @@
 pub use non_zero [NonZero]
+use std:string [<+>]
 use std:io [crash]
 
 when n can Num + Negate + Compare
@@ -59,13 +60,13 @@ pub trait Compare
 when a can ToString
 fn or_overflow_error char lhs rhs (n, overflown) as u8, a, a, (a, bool) -> a =
   if overflown
-    then crash ("integer overflow " <++> show lhs <++> " " <+> char <++> " " <++> show rhs)
+    then crash ("integer overflow " <> lhs <> " " <+> char <> " " <> show rhs)
     else n
 
 when a can ToString
 fn or_underflow_error char lhs rhs (n, underflown) as u8, a, a, (a, bool) -> a =
   if underflown
-    then crash ("integer underflow " <++> show lhs <++> " " <+> char <++> " " <++> show rhs)
+    then crash ("integer underflow " <> lhs <> " " <+> char <> " " <> rhs)
     else n
 
 impl Num for u8

luminapath/std/prelude/lib.lm

@@ -9,7 +9,7 @@ pub use std:math:i32
 pub use std:math:i64
 pub use std:maybe [Maybe [..]]
 pub use std:result [Result [..]]
-pub use std:string [string, ToString [show], <:>, <++>, <+>]
+pub use std:string [string, ToString [show], <>]
 pub use std:list [Listable [:], List, ++]
 use std:string [Stringable]
 pub use std:nothing [nothing]

luminapath/std/result/lib.lm

@@ -21,7 +21,7 @@ when e can ToString
 pub fn or_crash msg r as string, Result a e -> a =
   match r
   | Ok v    -> v
-  | Err err -> io:crash (msg <++> ": " <++> show err)
+  | Err err -> io:crash (msg <> ": " <> show err)
 
 pub fn or_crash_ msg r as string, Result a e -> a =
   match r

luminapath/std/string/lib.lm

@@ -83,6 +83,12 @@ pub fn to_c_str str as string -> *u8 =
 pub trait ToString
   fn show as self -> string
 
+when
+  a can ToString
+  b can ToString
+pub fn <> left right as a, b -> string =
+  show left <++> show right
+
 pub fn <:> left right as u8, string -> string =
   { string | inner = left : right.inner }
 

luminapath/std/string/num.lm

@@ -1,3 +1,5 @@
+use std:string [<:>, <+>]
+
 impl ToString for i64
   fn show n = 
     let str = show ((std:math:i64:abs n) as u64) in

luminapath/std/tuple/lib.lm

@@ -1,17 +1,21 @@
+use std:string [<++>]
+
+// TODO: using `<>` instead of `<++>` here causes bools to display as ints. 
+// That does not make any sense, and must be some sort of problem with our trait solver? 
 when
   a can ToString
   b can ToString
 impl ToString for (a, b)
   fn show (a, b) as (a, b) -> string =
-    "(" <++> show a <++> ", " <++> show b <++> ")"
+    "(" <++> show a <++> show ", " <++> show b <++> show ")"
 
 when
   a can ToString
   b can ToString
   c can ToString
 impl ToString for (a, b, c)
   fn show (a, b, c) as (a, b, c) -> string =
-    "(" <++> show a <++> ", " <++> show b <++> ", " <++> show c <++> ")"
+    "(" <++> show a <++> show ", " <++> show b <++> show ", " <++> show c <++> show ")"
 
 when
   a can ToString
@@ -20,7 +24,7 @@ when
   d can ToString
 impl ToString for (a, b, c, d)
   fn show (a, b, c, d) as (a, b, c, d) -> string =
-    "(" <++> show a <++> ", " <++> show b <++> ", " <++> show c <++> ", " <++> show d <++> ")"
+    "(" <++> show a <++> show ", " <++> show b <++> show ", " <++> show c <++> show ", " <++> show d <++> show ")"
 
 when
   a can ToString
@@ -30,7 +34,7 @@ when
   e can ToString
 impl ToString for (a, b, c, d, e)
   fn show (a, b, c, d, e) as (a, b, c, d, e) -> string =
-    "(" <++> show a <++> ", " <++> show b <++> ", " <++> show c <++> ", " <++> show d <++> ", " <++> show e <++> ")"
+    "(" <++> show a <++> show ", " <++> show b <++> show ", " <++> show c <++> show ", " <++> show d <++> show ", " <++> show e <++> show ")"
 
 when
   a can ToString
@@ -41,4 +45,4 @@ when
   f can ToString
 impl ToString for (a, b, c, d, e, f)
   fn show (a, b, c, d, e, f) as (a, b, c, d, e, f) -> string =
-    "(" <++> show a <++> ", " <++> show b <++> ", " <++> show c <++> ", " <++> show d <++> ", " <++> show e <++> ", " <++> show f <++> ")"
+    "(" <++> show a <++> show ", " <++> show b <++> show ", " <++> show c <++> show ", " <++> show d <++> show ", " <++> show e <++> show ", " <++> show f <++> show ")"