Implement simplex install std command

README.md

@@ -115,7 +115,7 @@ Simplex CLI provides the following commands:
 
 - `simplex init` - Initializes a new Simplex project.
 - `simplex config` - Prints the current config.
-- `simplex install <dep>` - Installs SimplicityHL dependencies. Without a `<dep>` provided, installs everything listed in the `[dependencies]` config section. With one or more `<dep>` arguments, appends new entries to the config and then installs everything.
+- `simplex install <dep>` - Installs SimplicityHL dependencies. Without a `<dep>` provided, installs everything listed in the `[dependencies]` config section. With one or more `<dep>` arguments, appends new entries to the config and then installs everything. The bare name `std` pins the latest `SimplicityHL` [standard library](https://github.com/BlockstreamResearch/simplicityhl-std) release.
 - `simplex build` - Generates simplicity artifacts.
 - `simplex regtest` - Spins up local Electrs + Elements nodes.
 - `simplex test` - Runs Simplex tests.

crates/build/src/config/dep_spec.rs

@@ -1,21 +1,31 @@
 use std::fmt::Write;
+use std::process::Command;
+
+use toml_edit::{InlineTable, Value};
 
 use crate::error::TomlEditError;
 
+/// The bare token that resolves to the `SimplicityHL` standard library.
+const STD_ALIAS: &str = "std";
+
+/// The repository backing [`STD_ALIAS`].
+const STD_URL: &str = "https://github.com/BlockstreamResearch/simplicityhl-std.git";
+
 pub(super) struct DepSpec {
     pub alias: String,
     pub source: Source,
 }
 
 pub(super) enum Source {
-    Git(String),
+    Git { url: String, tag: Option<String> },
     Path(String),
 }
 
 impl DepSpec {
     /// Parses a raw CLI token into a [`DepSpec`].
     ///
     /// Accepted forms:
+    /// - `std`: Shorthand for [`STD_URL`], pinned to its latest release tag.
     /// - `<source>`: The alias is derived from the last path segment of the source,
     ///   with a trailing `.git` stripped.
     /// - `<alias>=<source>`: Both parts must be non-empty.
@@ -27,7 +37,13 @@ impl DepSpec {
     /// - `TomlEditError::MalformedDep`: If `raw` contains `=` but either side is empty,
     ///   or if the alias cannot be derived from the source (e.g. the source contains
     ///   no non-empty path segment).
+    /// - `TomlEditError::RemoteTags` / `TomlEditError::NoTags`: If `raw` is `std` and
+    ///   its latest tag cannot be resolved.
     pub(super) fn parse_dep(raw: &str) -> Result<DepSpec, TomlEditError> {
+        if raw == STD_ALIAS {
+            return Self::std_spec();
+        }
+
         let (alias, source_str) = match raw.split_once('=') {
             Some((a, s)) if !a.is_empty() && !s.is_empty() => (a.to_owned(), s),
             Some(_) => return Err(TomlEditError::MalformedDep(raw.to_owned())),
@@ -39,6 +55,74 @@ impl DepSpec {
         Ok(DepSpec { alias, source })
     }
 
+    /// Builds the spec for the standard library, pinned to the newest tag currently
+    /// published by [`STD_URL`].
+    fn std_spec() -> Result<DepSpec, TomlEditError> {
+        let tag = Self::latest_tag(STD_URL)?;
+
+        Ok(DepSpec {
+            alias: STD_ALIAS.to_owned(),
+            source: Source::Git {
+                url: STD_URL.to_owned(),
+                tag: Some(tag),
+            },
+        })
+    }
+
+    /// Returns the highest release tag advertised by the remote at `url`.
+    ///
+    /// # Errors
+    /// - `TomlEditError::RemoteTags`: If `git ls-remote` cannot be run, exits non-zero,
+    ///   or emits non-UTF-8 output.
+    /// - `TomlEditError::NoTags`: If the remote advertises no release tag.
+    fn latest_tag(url: &str) -> Result<String, TomlEditError> {
+        let failed = |reason: String| TomlEditError::RemoteTags {
+            url: url.to_owned(),
+            reason,
+        };
+
+        let output = Command::new("git")
+            .args(["ls-remote", "--tags", "--refs", "--sort=-v:refname", url])
+            .output()
+            .map_err(|err| failed(err.to_string()))?;
+
+        if !output.status.success() {
+            return Err(failed(String::from_utf8_lossy(&output.stderr).trim().to_owned()));
+        }
+
+        let stdout = String::from_utf8(output.stdout).map_err(|err| failed(err.to_string()))?;
+
+        stdout
+            .lines()
+            .filter_map(|line| line.split_once('\t'))
+            .filter_map(|(_, reference)| reference.strip_prefix("refs/tags/"))
+            // skip pre-releases
+            .find(|tag| !tag.contains('-'))
+            .map(str::to_owned)
+            .ok_or_else(|| TomlEditError::NoTags(url.to_owned()))
+    }
+
+    /// Renders the spec as the inline table written under `[dependencies]`.
+    #[must_use]
+    pub(super) fn to_inline(&self) -> InlineTable {
+        let mut inline = InlineTable::new();
+
+        match &self.source {
+            Source::Git { url, tag } => {
+                inline.insert("git", Value::from(url.as_str()));
+
+                if let Some(tag) = tag {
+                    inline.insert("tag", Value::from(tag.as_str()));
+                }
+            }
+            Source::Path(p) => {
+                inline.insert("path", Value::from(p.as_str()));
+            }
+        }
+
+        inline
+    }
+
     /// Formats a batch of dependency specs as a bracketed, one-per-line list.
     #[must_use]
     pub(super) fn format_batch(specs: &[DepSpec]) -> String {
@@ -53,11 +137,7 @@ impl DepSpec {
                 out.push(',');
             }
 
-            let source = match &spec.source {
-                Source::Git(url) => url.as_str(),
-                Source::Path(p) => p.as_str(),
-            };
-            let _ = write!(out, "\n    {} = {}", spec.alias, source);
+            let _ = write!(out, "\n    {} = {}", spec.alias, spec.to_inline());
         }
 
         out.push_str("\n]");
@@ -94,7 +174,10 @@ impl DepSpec {
             || s.starts_with("ssh://")
             || git_ext
         {
-            Source::Git(s.to_owned())
+            Source::Git {
+                url: s.to_owned(),
+                tag: None,
+            }
         } else {
             Source::Path(s.to_owned())
         }

crates/build/src/config/dependency.rs

@@ -1,12 +1,11 @@
 use std::collections::HashMap;
 use std::path::Path;
 
-use toml_edit::{DocumentMut, InlineTable, Item, Value};
+use toml_edit::{DocumentMut, Item};
 
 use serde::Deserialize;
 
 use super::dep_spec::DepSpec;
-use super::dep_spec::Source;
 
 use crate::error::{BuildError, DependencyValidationError, TomlEditError};
 
@@ -103,31 +102,12 @@ impl DependencyConfig {
             .as_table_mut()
             .ok_or(TomlEditError::MalformedDependenciesTable)?;
 
-        // Batches are small (typically <=10), so a linear scan over a Vec is cheaper
-        // than the constant overhead of a HashSet.
-        let mut seen_in_batch: Vec<&str> = Vec::with_capacity(specs.len());
-
         for spec in &specs {
-            if seen_in_batch.contains(&spec.alias.as_str()) || deps_table.contains_key(&spec.alias) {
+            if deps_table.contains_key(&spec.alias) {
                 return Err(TomlEditError::DuplicateAlias(spec.alias.clone()));
             }
 
-            seen_in_batch.push(spec.alias.as_str());
-        }
-
-        for spec in &specs {
-            let mut inline = InlineTable::new();
-
-            match &spec.source {
-                Source::Git(url) => {
-                    inline.insert("git", Value::from(url.as_str()));
-                }
-                Source::Path(p) => {
-                    inline.insert("path", Value::from(p.as_str()));
-                }
-            }
-
-            deps_table.insert(&spec.alias, Item::Value(Value::InlineTable(inline)));
+            deps_table.insert(&spec.alias, Item::Value(spec.to_inline().into()));
         }
 
         std::fs::write(path, doc.to_string())?;

crates/build/src/error.rs

@@ -42,6 +42,12 @@ pub enum TomlEditError {
 
     #[error("dependency `{0}` already exists")]
     DuplicateAlias(String),
+
+    #[error("failed to list the tags of `{url}`: {reason}")]
+    RemoteTags { url: String, reason: String },
+
+    #[error("`{0}` publishes no release tag")]
+    NoTags(String),
 }
 
 #[derive(thiserror::Error, Debug)]

crates/cli/src/commands/core.rs

@@ -23,6 +23,7 @@ pub enum Command {
     /// If `deps` is empty, install everything from `Simplex.toml`.
     Install {
         /// Dependencies to install, as `<source>` or `<alias>=<source>`.
+        /// The bare name `std` pins the latest `SimplicityHL` standard library release.
         #[arg(value_name = "DEP")]
         deps: Vec<String>,
     },