X-Git-Url: http://git.annexia.org/?a=blobdiff_plain;f=stdlib%2Fprelude.gl;h=32adf5c827346e5f330a5d9eba55f0f10724009f;hb=830b616204b3c08429440381349c86c8073ac161;hp=e8a96e896788493cc064d513c8ad479a7c42e374;hpb=be61a8a416b1bef88a416579cc663f1849ccf1cf;p=goals.git

diff --git a/stdlib/prelude.gl b/stdlib/prelude.gl
index e8a96e8..32adf5c 100644
--- a/stdlib/prelude.gl
+++ b/stdlib/prelude.gl
@@ -18,10 +18,10 @@
 
 # This file is included first and automatically in all Goalfiles
 # (unless you use --no-prelude).  It contains standard functions and
-# tactics.
+# predicates.
 
-# The only tactic that ‘make’ has.
-tactic *file (filename) = @{
+# The only predicate that ‘make’ has.
+predicate is-file (filename) = @{
     # Rebuild if the target file doesn't exist at all.
     test -f %filename || exit 99
 
@@ -31,9 +31,9 @@ tactic *file (filename) = @{
     done
 }
 
-# This is a simpler tactic than the above since it will
+# This is a simpler predicate than the above since it will
 # rebuild if the file is missing, but not if it is older.
-tactic *exists (filename) = @{
+predicate is-file-exists (filename) = @{
     test -f %filename || exit 99
 }
 
@@ -45,7 +45,7 @@ function error (msg) = @{
     exit 1
 }
 
-# Wrap list of strings in a call or tactic.
+# Wrap list of strings in a call or predicate.
 pure function wrap (wrapper, xs) = @{
     echo '['
     for x in %xs; do
@@ -59,6 +59,16 @@ pure function wrap (wrapper, xs) = @{
 #----------------------------------------------------------------------
 # Text functions.
 
+# Filter a list by regexp.
+pure function filter (pat, xs) returning strings = @{
+    for f in %xs; do echo "$f"; done | grep -E -- %pat
+}
+
+# Filter out a list by regexp.
+pure function filter-out (pat, xs) returning strings = @{
+    for f in %xs; do echo "$f"; done | grep -v -E -- %pat
+}
+
 # Head of a list.
 pure function head (xs) returning string = @{
     for f in %xs; do
@@ -72,11 +82,37 @@ pure function join (xs, ys) returning strings = @{
     for f in %xs %ys; do echo "$f"; done
 }
 
+# Last element of a list.
+pure function last (xs) returning string = @{
+    for f in %xs; do
+        r="$f"
+    done
+    echo "$r"
+}
+
+# n'th element of a list.
+pure function nth (n, xs) returning string = @{
+    i=0
+    r=
+    for f in %xs; do
+        if [ $i -eq %n ]; then r="$f"; fi
+        ((++i))
+    done
+    echo "$r"
+}
+
 # Sort + uniq a list.
 pure function sort (xs) returning strings = @{
     for f in %xs; do echo "$f"; done | sort -u
 }
 
+# Split a string into a list.
+# https://superuser.com/a/1066541
+pure function split (s) returning strings = @{
+    s=%s
+    eval 'for f in '$s'; do echo "$f"; done'
+}
+
 # Substitute.
 pure function subst (from, to, text) returning string = @{
     # We need to replace any / characters in ‘to’ with escaped ones.